Methods of and systems for materials processing using optical beams

ABSTRACT

A method of materials processing using an optical beam includes: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP; modifying one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP can be the same as or differ from the second RIP. The modifying of the one or more beam characteristics can include changing the one or more beam characteristics from a first state to a second state. The first state can differ from the second state.

RELATED APPLICATIONS

This application is a continuation-in-part of international applicationPCT/US2017/034848, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. Thisapplication is a continuation-in-part of U.S. patent application Ser.No. 15/607,411, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. Thisapplication is a continuation-in-part of U.S. patent application Ser.No. 15/607,410, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. Thisapplication is a continuation-in-part of U.S. patent application Ser.No. 15/607,399, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. All of theabove applications are herein incorporated by reference in theirentireties.

TECHNICAL FIELD

The subject matter disclosed herein generally relates to methods of andsystems for materials processing using optical beams. The subject matterdisclosed herein also relates to methods of and systems for materialsprocessing using optical beams using laser beams, such as fiber-coupledlasers (e.g., diode lasers, fiber lasers, yttrium aluminum garnet(“YAG”) lasers) or diode lasers (e.g., fiber-coupled diode lasers,free-space diode lasers).

BACKGROUND

The use of high-power fiber-coupled lasers continues to gain popularityfor a variety of applications, such as materials processing involving,for example, brazing, cladding, glazing, heat treating, and welding.These lasers include, for example, fiber lasers, disk lasers, diodelasers, diode-pumped solid state lasers, and lamp-pumped solid statelasers. In these systems, optical power is delivered from the laser to awork piece via an optical fiber.

Various fiber-coupled laser materials processing tasks can requiredifferent beam characteristics (e.g., spatial profiles and/or divergenceprofiles). For example, cutting thick metal and welding generallyrequire a larger spot size than cutting thin metal. Ideally, the laserbeam properties would be adjustable to enable optimized processing forthese different tasks. Conventionally, users have two choices: (1)employ a laser system with fixed beam characteristics that can be usedfor different tasks but is not optimal for most of them (i.e., acompromise between performance and flexibility); or (2) purchase a lasersystem or accessories that offer variable beam characteristics but thatadd significant cost, size, weight, complexity, and perhaps performancedegradation (e.g., optical loss or reduced speed due to delays involvedwhile varying beam characteristics) or reliability degradation (e.g.,reduced robustness or up-time). Currently available laser systemscapable of varying beam characteristics typically require the use offree-space optics or other complex and expensive add-on mechanisms(e.g., zoom lenses, mirrors, translatable or motorized lenses,combiners, etc.) in order to vary beam characteristics. No solutionappears to exist which provides the desired adjustability in beamcharacteristics that minimizes or eliminates reliance on the use offree-space optics or other extra components that add significantpenalties in terms of cost, complexity, performance, and/or reliability.Thus, the industry needs an in-fiber apparatus for providing varyingbeam characteristics that does not require or minimizes the use offree-space optics and that can avoid significant cost, complexity,performance tradeoffs, and/or reliability degradation.

In addition, the effectiveness and efficiency of applications such asmaterials processing involving, for example, brazing, cladding, glazing,heat treating, and welding, can be improved by providing the capabilityto manipulate beam characteristics tailored to the task at hand. Thus,the industry needs an in-fiber apparatus for providing varying beamcharacteristics consistently, predictably, and quickly.

SUMMARY

At least disclosed herein are methods of and systems for materialsprocessing using optical beams.

In some examples, a method of materials processing using an optical beamcan comprise: launching the optical beam into a first length of fiberhaving a first refractive-index profile (RIP); coupling the optical beamfrom the first length of fiber into a second length of fiber having asecond RIP and one or more confinement regions; modifying one or morebeam characteristics of the optical beam in the first length of fiber,in the second length of fiber, or in the first and second lengths offiber; and/or generating an output beam, having the modified one or morebeam characteristics of the optical beam, from the second length offiber. The first RIP can differ from the second RIP. The modifying ofthe one or more beam characteristics can comprise changing the one ormore beam characteristics from a first state to a second state. Thefirst state can differ from the second state.

In some examples, the method can further comprise: confining themodified one or more beam characteristics of the optical beam within theone or more confinement regions of the second length of fiber.

In some examples, the method can further comprise: using the output beamfor one or more of brazing, cladding, glazing, heat-treating, orwelding, or any combination thereof, one or more materials.

In some examples, the modifying of the one or more beam characteristicscan further comprise adjusting the one or more beam characteristics,during processing of one or more materials, based on in-process feedbackfrom one or more sensors.

In some examples, the modifying of the one or more beam characteristicscan further comprise adjusting the one or more beam characteristics,between steps of processing one or more materials, based on feedbackfrom one or more sensors.

In some examples, the modifying of the one or more beam characteristicscan further comprise adjusting a perturbation device in one or morediscrete steps in order to change the one or more beam characteristicsfrom the first state to the second state.

In some examples, the modifying of the one or more beam characteristicsfurther comprises adjusting a perturbation device in a continuous mannerin order to change the one or more beam characteristics from the firststate to the second state.

In some examples, a beam shape of the output beam can be asymmetric.

In some examples, the method can further comprise: changing a traveldirection of the output beam along one or more materials, during thematerials processing, from a first direction to a second direction. Thefirst direction can differ from the second direction.

In some examples, the second direction can be opposite to the firstdirection.

In some examples, a method of materials processing using an optical beammay comprise: launching the optical beam into a first length of fiberhaving a first refractive-index profile (RIP); coupling the optical beamfrom the first length of fiber into a second length of fiber having asecond RIP and two or more confinement regions; modifying one or morebeam characteristics of the optical beam in the first length of fiber,in the second length of fiber, or in the first and second lengths offiber; and/or generating an output beam, having the modified one or morebeam characteristics of the optical beam, from the second length offiber. The first RIP can be the same as the second RIP. The modifying ofthe one or more beam characteristics can comprise changing the one ormore beam characteristics from a first state to a second state. Thefirst state can differ from the second state.

In some examples, the method can further comprise: confining themodified one or more beam characteristics of the optical beam within theone or more confinement regions of the second length of fiber.

In some examples, the method can further comprise: using the output beamfor one or more of brazing, cladding, glazing, heat-treating, orwelding, or any combination thereof, one or more materials.

In some examples, the modifying of the one or more beam characteristicscan further comprise adjusting the one or more beam characteristics,during processing of one or more materials, based on in-process feedbackfrom one or more sensors.

In some examples, the modifying of the one or more beam characteristicscan further comprise adjusting the one or more beam characteristics,between steps of processing one or more materials, based on feedbackfrom one or more sensors.

In some examples, the modifying of the one or more beam characteristicscan further comprise adjusting a perturbation device in one or morediscrete steps in order to change the one or more beam characteristicsfrom the first state to the second state.

In some examples, the modifying of the one or more beam characteristicscan further comprise adjusting a perturbation device in a continuousmanner in order to change the one or more beam characteristics from thefirst state to the second state.

In some examples, a beam shape of the output beam can be asymmetric.

In some examples, the method can further comprise: changing a traveldirection of the output beam along one or more materials, during thematerials processing, from a first direction to a second direction. Thefirst direction can differ from the second direction.

In some examples, the second direction can be opposite to the firstdirection.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the present teachings, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages will become more apparentand more readily appreciated from the following detailed description ofexamples, taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an example fiber structure for providing a laser beamhaving variable beam characteristics;

FIG. 2 depicts a cross-sectional view of an example fiber structure fordelivering a beam with variable beam characteristics;

FIG. 3 illustrates an example method of perturbing a fiber structure forproviding a beam having variable beam characteristics;

FIG. 4 is a graph illustrating the calculated spatial profile of thelowest-order mode (LP₀₁) for a first length of a fiber for differentfiber bend radii;

FIG. 5 illustrates an example of a two-dimensional intensitydistribution at a junction when a fiber for varying beam characteristicsis nearly straight;

FIG. 6 illustrates an example of a two-dimensional intensitydistribution at a junction when a fiber for varying beam characteristicsis bent with a radius chosen to preferentially excite a particularconfinement region of a second length of fiber;

FIGS. 7-10 depict experimental results to illustrate further outputbeams for various bend radii of a fiber for varying beam characteristicsshown in FIG. 2;

FIGS. 11-16 illustrate cross-sectional views of example first lengths offiber for enabling adjustment of beam characteristics in a fiberassembly;

FIGS. 17-19 illustrate cross-sectional views of example second lengthsof fiber (“confinement fibers”) for confining adjusted beamcharacteristics in a fiber assembly;

FIGS. 20 and 21 illustrate cross-sectional views of example secondlengths of fiber for changing a divergence angle of and confining anadjusted beam in a fiber assembly configured to provide variable beamcharacteristics;

FIG. 22A illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and process head;

FIG. 22B illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and process head;

FIG. 23 illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and multiple process fibers;

FIG. 24 illustrates examples of various perturbation assemblies forproviding variable beam characteristics according to various examplesprovided herein;

FIG. 25 illustrates an example process for adjusting and maintainingmodified characteristics of an optical beam;

FIGS. 26-28 are cross-sectional views illustrating example secondlengths of fiber (“confinement fibers”) for confining adjusted beamcharacteristics in a fiber assembly;

FIG. 29 depicts a first example method of materials processing usingoptical beams;

FIG. 30 depicts a second example method of materials processing usingoptical beams;

FIG. 31 depicts a first example apparatus for materials processing usingoptical beams;

FIG. 32 depicts a second example apparatus for materials processingusing optical beams;

FIG. 33 depicts a third example apparatus for materials processing usingoptical beams;

FIGS. 34A and 34B depict example output beams having two discrete spotshapes; and

FIGS. 35A-35D depict example output beams having two discrete spotshapes.

DETAILED DESCRIPTION

Exemplary aspects will now be described more fully with reference to theaccompanying drawings. Examples of the disclosure, however, can beembodied in many different forms and should not be construed as beinglimited to the examples set forth herein. Rather, these examples areprovided so that this disclosure will be thorough and complete, and willfully convey the scope to one of ordinary skill in the art. In thedrawings, some details may be simplified and/or may be drawn tofacilitate understanding rather than to maintain strict structuralaccuracy, detail, and/or scale. For example, the thicknesses of layersand regions may be exaggerated for clarity.

It will be understood that when an element is referred to as being “on,”“connected to,” “electrically connected to,” or “coupled to” to anothercomponent, it may be directly on, connected to, electrically connectedto, or coupled to the other component or intervening components may bepresent. In contrast, when a component is referred to as being “directlyon,” “directly connected to,” “directly electrically connected to,” or“directly coupled to” another component, there are no interveningcomponents present. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers, and/or sections, these elements, components, regions,layers, and/or sections should not be limited by these terms. Theseterms are only used to distinguish one element, component, region,layer, and/or section from another element, component, region, layer,and/or section. For example, a first element, component, region, layer,or section could be termed a second element, component, region, layer,or section without departing from the teachings of examples.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like may be used herein for ease of description todescribe the relationship of one component and/or feature to anothercomponent and/or feature, or other component(s) and/or feature(s), asillustrated in the drawings. It will be understood that the spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation(s) depicted inthe figures.

The terminology used herein is for the purpose of describing particularexamples only and is not intended to be limiting of examples. As usedherein, the singular forms “a,” “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Although the operations of some of the disclosed methods are describedin a particular, sequential order for convenient presentation, it shouldbe understood that this manner of description encompasses rearrangement,unless a particular ordering is required by specific language set forthbelow. For example, operations described sequentially may in some casesbe rearranged or performed concurrently. Moreover, for the sake ofsimplicity, the attached figures may not show the various ways in whichthe disclosed systems, methods, and apparatuses can be used inconjunction with other systems, methods, and apparatuses. Additionally,the description sometimes uses terms like “produce” and “provide” todescribe the disclosed methods. These terms are high-level abstractionsof the actual operations that are performed. The actual operations thatcorrespond to these terms will vary depending on the particularimplementation and are readily discernible by a person of ordinary skillin the art.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as understood by one ofordinary skill in the art. It will be further understood that terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

The present disclosure is directed to methods of and systems forprocessing using adjustable beam characteristics.

Definitions

Definitions of words and terms as used herein:

-   1. The term “beam characteristics” refers to one or more of the    following terms used to describe an optical beam. In general, the    beam characteristics of most interest depend on the specifics of the    application or optical system.-   2. The term “beam diameter” is defined as the distance across the    center of the beam along an axis for which the irradiance    (intensity) equals 1/e² of the maximum irradiance. While examples    disclosed herein generally use beams that propagate in azimuthally    symmetric modes, elliptical or other beam shapes can be used, and    beam diameter can be different along different axes. Circular beams    are characterized by a single beam diameter. Other beam shapes can    have different beam diameters along different axes.-   3. The term “spot size” is the radial distance (radius) from the    center point of maximum irradiance to the 1/e² point.-   4. The term “beam divergence distribution” is the power vs the full    cone angle. This quantity is sometimes called the “angular    distribution” or “NA distribution.”-   5. The term “beam parameter product” (“BPP”) of a laser beam is    defined as the product of the beam radius (measured at the beam    waist) and the beam divergence half-angle (measured in the far    field). The units of BPP are typically millimeters-milliradians    (“mm-mrad”).-   6. A “confinement fiber” is defined to be a fiber that possesses one    or more confinement regions, wherein a confinement region comprises    a higher-index region (core region) surrounded by a lower-index    region (cladding region). The RIP of a confinement fiber may include    one or more higher-index regions (core regions) surrounded by    lower-index regions (cladding regions), wherein light is guided in    the higher-index regions. Each confinement region and each cladding    region can have any RIP, including but not limited to step-index and    graded-index. The confinement regions may or may not be concentric    and may be a variety of shapes such as circular, annular, polygonal,    arcuate, elliptical, irregular, or the like, or any combination    thereof. The confinement regions in a particular confinement fiber    may all have the same shape or may be different shapes. Moreover,    confinement regions may be co-axial or may have offset axes with    respect to one another. Confinement regions may be of uniform    thickness about a central axis in the longitudinal direction, or the    thicknesses may vary about the central axis in the longitudinal    direction.-   7. The term “intensity distribution” refers to optical intensity as    a function of position along a line (one-dimensional (“1D”) profile)    or in a plane (two-dimensional (“2D”) profile). The line or plane is    usually taken perpendicular to the propagation direction of the    light. It is a quantitative property.-   8. “Luminance” is a photometric measure of the luminous intensity    per unit area of light travelling in a given direction.-   9. “M² factor” (also called “beam quality factor” or “beam    propagation factor”) is a dimensionless parameter for quantifying    the beam quality of laser beams, with M²=1 being a    diffraction-limited beam, and larger values of the M² factor    corresponding to lower beam quality. M² is equal to the BPP divided    by λ/π, where λ is the wavelength of the beam in microns (if BPP is    expressed in units of mm-mrad).-   10. The term “numerical aperture” or “NA” of an optical system is a    dimensionless number that characterizes the range of angles over    which the system can accept or emit light.-   11. The term “optical intensity” is not an official (SI) unit, but    is used to denote incident power per unit area on a surface or    passing through a plane.-   12. The term “power density” refers to optical power per unit area,    although this is also referred to as “optical intensity.”-   13. The term “radial beam position” refers to the position of a beam    in a fiber measured with respect to the center of the fiber core in    a direction perpendicular to the fiber axis.-   14. “Radiance” is the radiation emitted per unit solid angle in a    given direction by a unit area of an optical source (e.g., a laser).    Radiance may be altered by changing the beam intensity distribution    and/or beam divergence profile or distribution. The ability to vary    the radiance profile of a laser beam implies the ability to vary the    BPP.-   15. The term “refractive-index profile” or “RIP” refers to the    refractive index as a function of position along a line (1D) or in a    plane (2D) perpendicular to the fiber axis. Many fibers are    azimuthally symmetric, in which case the 1D RIP is identical for any    azimuthal angle.-   16. A “step-index fiber” has a RIP that is flat (refractive index    independent of position) within the fiber core.-   17. A “graded-index fiber” has a RIP in which the refractive index    decreases with increasing radial position (i.e., with increasing    distance from the center of the fiber core).-   18. A “parabolic-index fiber” is a specific case of a graded-index    fiber in which the refractive index decreases quadratically with    increasing distance from the center of the fiber core.-   19. The term “additive manufacturing” refers to processes of joining    materials to make parts from three-dimensional (“3D”) model data,    usually layer upon layer, as opposed to subtractive manufacturing    and formative manufacturing methodologies. Powder bed fusion, for    example, is one common additive material process.-   20. The terms “fuse” and “fusing” refer to sintering, melting (e.g.,    partially or fully melting), chemical bonding, or any other    phenomena in which particles are joined together using heat (e.g.,    coalescence of two or more materials due to application of heat).-   21. The term “melt pool” refers to a substantially liquid mixture of    materials being processed, feedstock, and/or filler caused by the    absorption of heat from an optical beam or another heat source (also    known in the industry as “fusion zone”, “molten pool”, or “weld    pool”).    Fiber for Varying Beam Characteristics

Disclosed herein are methods, systems, and apparatus configured toprovide a fiber operable to provide a laser beam having variable beamcharacteristics (“VBC”) that may reduce cost, complexity, optical loss,or other drawbacks of the conventional methods described above. This VBCfiber is configured to vary a wide variety of optical beamcharacteristics. Such beam characteristics can be controlled using theVBC fiber thus allowing users to tune various beam characteristics tosuit the particular requirements of an extensive variety of laserprocessing applications. For example, a VBC fiber may be used to tune:beam diameter, beam divergence distribution, BPP, intensitydistribution, M² factor, NA, optical intensity, power density, radialbeam position, radiance, spot size, or the like, or any combinationthereof.

In general, the disclosed technology entails coupling a laser beam intoa fiber in which the characteristics of the laser beam in the fiber canbe adjusted by perturbing the laser beam and/or perturbing a firstlength of fiber by any of a variety of methods (e.g., bending the fiberor introducing one or more other perturbations) and fully or partiallymaintaining adjusted beam characteristics in a second length of fiber.The second length of fiber is specially configured to maintain and/orfurther modify the adjusted beam characteristics. In some cases, thesecond length of fiber preserves the adjusted beam characteristicsthrough delivery of the laser beam to its ultimate use (e.g., materialsprocessing). The first and second lengths of fiber may comprise the sameor different fibers.

The disclosed technology is compatible with fiber-coupled lasers (e.g.,diode lasers, fiber lasers). Fiber-coupled lasers typically deliver anoutput via a delivery fiber having a step-index refractive index profile(“RIP”), i.e., a flat or constant refractive index within the fibercore. In reality, the RIP of the delivery fiber may not be perfectlyflat, depending on the design of the fiber. Important parameters are thefiber core diameter (“d_(core)”) and NA. The core diameter is typicallyin the range of 10-1000 microns (although other values are possible),and the NA is typically in the range of 0.06-0.22 (although other valuesare possible). A delivery fiber from the laser may be routed directly tothe process head or work piece, or it may be routed to a fiber-to-fibercoupler (“FFC”) or fiber-to-fiber switch (“FFS”), which couples thelight from the delivery fiber into a process fiber that transmits thebeam to the process head or the work piece.

Most materials processing tools, especially those at high power (>1kilowatt (“kW”)), employ multimode (“MM”) fiber, but some employsingle-mode (“SM”) fiber, which is at the lower end of the d_(core) andNA ranges. The beam characteristics from a SM fiber are uniquelydetermined by the fiber parameters. The beam characteristics from a MMfiber, however, can vary (unit-to-unit and/or as a function of laserpower and time), depending on the beam characteristics from the lasersource(s) coupled into the fiber, the launching or splicing conditionsinto the fiber, the fiber RIP, and the static and dynamic geometry ofthe fiber (bending, coiling, motion, micro-bending, etc.). For both SMand MM delivery fibers, the beam characteristics may not be optimum fora given materials processing task, and it is unlikely to be optimum fora range of tasks, motivating the desire to be able to systematicallyvary the beam characteristics in order to customize or optimize them fora particular processing task.

In one example, the VBC fiber may have a first length and a secondlength and may be configured to be interposed as an in-fiber devicebetween the delivery fiber and the process head to provide the desiredadjustability of the beam characteristics. To enable adjustment of thebeam, a perturbation device and/or assembly is disposed in closeproximity to and/or coupled with the VBC fiber and is responsible forperturbing the beam in a first length such that the beam'scharacteristics are altered in the first length of fiber, and thealtered characteristics are preserved or further altered as the beampropagates in the second length of fiber. The perturbed beam is launchedinto a second length of the VBC fiber configured to conserve adjustedbeam characteristics. The first and second lengths of fiber may be thesame or different fibers and/or the second length of fiber may comprisea confinement fiber. The beam characteristics that are conserved by thesecond length of VBC fiber may include any of: angular distribution,azimuthal intensity distribution, beam diameter, beam divergencedistribution, BPP, beam profile (e.g., Gaussian, flat-top), beam shape,divergence, divergence profile, intensity distribution, luminance, M²factor, NA, optical intensity profile, optical mode (e.g., filtering),power density profile, radial beam position, radiance, spatial profiledistribution, spot shape, spot size, or the like, or any combinationthereof.

FIG. 1 illustrates an example VBC fiber 100 for providing a laser beamhaving variable beam characteristics without requiring the use offree-space optics to change the beam characteristics. VBC fiber 100comprises a first length of fiber 104 and a second length of fiber 108.First length of fiber 104 and second length of fiber 108 may be the sameor different fibers and may have the same or different RIPs. The firstlength of fiber 104 and the second length of fiber 108 may be joinedtogether by a splice. First length of fiber 104 and second length offiber 108 may be coupled in other ways, may be spaced apart, or may beconnected via an interposing component such as another length of fiber,free-space optics, glue, index-matching material, or the like, or anycombination thereof.

A perturbation device 110 is disposed proximal to and/or envelopsperturbation region 106. Perturbation device 110 may be a device,assembly, in-fiber structure, and/or other feature. Perturbation device110 at least perturbs optical beam 102 in first length of fiber 104 orsecond length of fiber 108 or a combination thereof in order to adjustone or more beam characteristics of optical beam 102. Adjustment ofoptical beam 102 responsive to perturbation by perturbation device 110may occur in first length of fiber 104 or second length of fiber 108 ora combination thereof. Perturbation region 106 may extend over variouswidths and may or may not extend into a portion of second length offiber 108. As optical beam 102 propagates in VBC fiber 100, perturbationdevice 110 may physically act on VBC fiber 100 to perturb the fiber andadjust the characteristics of optical beam 102. Alternatively,perturbation device 110 may act directly on optical beam 102 to alterits beam characteristics. Subsequent to being adjusted, perturbed beam112 has different beam characteristics than optical beam 102, which willbe fully or partially conserved in second length of fiber 108. Inanother example, perturbation device 110 need not be disposed near asplice. Moreover, a splice may not be needed at all, for example VBCfiber 100 may be a single fiber, first length of fiber and second lengthof fiber could be spaced apart, or secured with a small gap (air-spacedor filled with an optical material, such as optical cement or anindex-matching material).

Perturbed beam 112 is launched into second length of fiber 108, whereperturbed beam 112 characteristics are largely maintained or continue toevolve as perturbed beam 112 propagates yielding the adjusted beamcharacteristics at the output of second length of fiber 108. In oneexample, the new beam characteristics may include an adjusted intensitydistribution. In an example, an altered beam intensity distribution willbe conserved in various structurally bounded confinement regions ofsecond length of fiber 108. Thus, the beam intensity distribution may betuned to a desired beam intensity distribution optimized for aparticular laser processing task. In general, the intensity distributionof perturbed beam 112 will evolve as it propagates in the second lengthof fiber 108 to fill the confinement region(s) into which perturbed beam112 is launched responsive to conditions in first length of fiber 104and perturbation caused by perturbation device 110. In addition, theangular distribution may evolve as the beam propagates in the secondfiber, depending on launch conditions and fiber characteristics. Ingeneral, fibers largely preserve the input divergence distribution, butthe distribution can be broadened if the input divergence distributionis narrow and/or if the fiber has irregularities or deliberate featuresthat perturb the divergence distribution. The various confinementregions, perturbations, and fiber features of second length of fiber 108are described in greater detail below. Optical beam 102 and perturbedbeam 112 are conceptual abstractions intended to illustrate how a beammay propagate through a VBC fiber 100 for providing variable beamcharacteristics and are not intended to closely model the behavior of aparticular optical beam.

VBC fiber 100 may be manufactured by a variety of methods includingPlasma Chemical Vapor Deposition (“PCVD”), Outside Vapor Deposition(“OVD”), Vapor Axial Deposition (“VAD”), Metal-Organic Chemical VaporDeposition (“MOCVD”), and/or Direct Nanoparticle Deposition (“DND”). VBCfiber 100 may comprise a variety of materials. For example, VBC fiber100 may comprise SiO₂, SiO₂ doped with GeO₂, germanosilicate, phosphoruspentoxide, phosphosilicate, Al₂O₃, aluminosilicate, or the like, or anycombination thereof. Confinement regions may be bounded by claddingdoped with fluorine, boron, or the like, or any combination thereof.Other dopants may be added to active fibers, including rare-earth ionssuch as Er³⁺ (erbium), Yb³⁺ (ytterbium), Nd³⁺ (neodymium), Tm³⁺(thulium), Ho³⁺ (holmium), or the like, or any combination thereof.Confinement regions may be bounded by cladding having a lower index thanthe confinement region with fluorine or boron doping. Alternatively, VBCfiber 100 may comprise photonic crystal fibers or micro-structuredfibers.

VBC fiber 100 is suitable for use in any of a variety of fiber, fiberoptic, or fiber laser devices, including continuous wave and pulsedfiber lasers, disk lasers, solid state lasers, or diode lasers (pulserate unlimited except by physical constraints). Furthermore,implementations in a planar waveguide or other types of waveguides andnot just fibers are within the scope of the claimed technology.

FIG. 2 depicts a cross-sectional view of an example VBC fiber 200 foradjusting beam characteristics of an optical beam. In an example, VBCfiber 200 may be a process fiber because it may deliver the beam to aprocess head for material processing. VBC fiber 200 comprises a firstlength of fiber 204 spliced at splice junction 206 to a second length offiber 208. A perturbation assembly 210 is disposed proximal to splicejunction 206. Perturbation assembly 210 may be any of a variety ofdevices configured to enable adjustment of the beam characteristics ofan optical beam 202 propagating in VBC fiber 200. In an example,perturbation assembly 210 may be a mandrel and/or another device thatmay provide means of varying the bend radius and/or bend length of VBCfiber 200 near the splice. Other examples of perturbation devices arediscussed below with respect to FIG. 24.

In an example, first length of fiber 204 has a parabolic-index first RIP212 as indicated by the left RIP graph. Most of the intensitydistribution of optical beam 202 is concentrated in the center of firstlength of fiber 204 when first length of fiber 204 is straight or nearlystraight. Second length of fiber 208 is a confinement fiber having asecond RIP 214 as shown in the right RIP graph. Second length of fiber208 includes confinement regions 216, 218, and 220. Confinement region216 is a central core surrounded by two annular (or ring-shaped)confinement regions 218 and 220. Layers 222 and 224 are structuralbarriers of lower index material between confinement regions 216, 218and/or 220, commonly referred to as “cladding” regions. In one example,layers 222 and 224 may comprise rings of fluorosilicate; in someembodiments, the fluorosilicate cladding layers are relatively thin.Other materials may be used as well and claimed subject matter is notlimited in this regard.

In an example, as optical beam 202 propagates along VBC fiber 200,perturbation assembly 210 may physically act on second length of fiber208 and/or optical beam 202 to adjust its beam characteristics andgenerate adjusted beam 226. In the current example, the intensitydistribution of optical beam 202 is modified by perturbation assembly210. Subsequent to adjustment of optical beam 202, the intensitydistribution of adjusted beam 226 may be concentrated in outerconfinement regions 218 and 220 with relatively little intensity in thecentral core confinement region 216. Because each of confinement regions216, 218, and/or 220 is isolated by the thin layers of lower indexmaterial in barrier layers 222 and 224, second length of fiber 208 cansubstantially maintain the adjusted intensity distribution of adjustedbeam 226. The beam will typically become distributed azimuthally withina given confinement region but will not transition (significantly)between the confinement regions as it propagates along the second lengthof fiber 208. Thus, the adjusted beam characteristics of adjusted beam226 are largely conserved within the isolated confinement regions 216,218, and/or 220. In some cases, it be may desirable to have the adjustedbeam 226 power divided among the confinement regions 216, 218, and/or220 rather than concentrated in a single region, and this condition maybe achieved by generating an appropriately adjusted beam 226.

In one example, central core confinement region 216 and annularconfinement regions 218 and 220 may be composed of fused silica glass,and cladding 222 and 224 defining the confinement regions may becomposed of fluorosilicate glass. Other materials may be used to formthe various confinement regions 216, 218, and/or 220, includinggermanosilicate, phosphosilicate, aluminosilicate, or the like, or acombination thereof, and claimed subject matter is not so limited. Othermaterials may be used to form the barrier rings 222 and/or 224,including fused silica, borosilicate, or the like, or a combinationthereof, and claimed subject matter is not so limited. In otherembodiments, the optical fibers or waveguides include or are composed ofvarious polymers, plastics, or crystalline materials. Generally, thecore confinement regions have refractive indices that are greater thanthe refractive indices of adjacent barrier/cladding regions.

In some examples, it may be desirable to increase a number ofconfinement regions in a second length of fiber to increase granularityof beam control over beam displacements for fine-tuning a beam profile.For example, confinement regions may be configured to provide stepwisebeam displacement.

FIG. 3 illustrates an example method of perturbing VBC fiber 200 forproviding variable beam characteristics of an optical beam. Changing thebend radius of a fiber may change the radial beam position, divergenceangle, and/or radiance profile of a beam within the fiber. The bendradius of VBC fiber 200 can be decreased from a first bend radius R₁ toa second bend radius R₂ about splice junction 206 by using a steppedmandrel or cone as the perturbation assembly 210. Additionally oralternatively, the engagement length on the mandrel(s) or cone can bevaried. Rollers 250 may be employed to engage VBC fiber 200 acrossperturbation assembly 210. In an example, an amount of engagement ofrollers 250 with VBC fiber 200 has been shown to shift the distributionof the intensity profile to the outer confinement regions 218 and 220 ofVBC fiber 200 with a fixed mandrel radius. There are a variety of othermethods for varying the bend radius of VBC fiber 200, such as using aclamping assembly, flexible tubing, or the like, or a combinationthereof, and claimed subject matter is not limited in this regard. Inanother example, for a particular bend radius the length over which VBCfiber 200 is bent can also vary beam characteristics in a controlled andreproducible way. In examples, changing the bend radius and/or lengthover which the fiber is bent at a particular bend radius also modifiesthe intensity distribution of the beam such that one or more modes maybe shifted radially away from the center of a fiber core.

Maintaining the bend radius of the fibers across splice junction 206ensures that the adjusted beam characteristics such as radial beamposition and radiance profile of optical beam 202 will not return tooptical beam 202's unperturbed state before being launched into secondlength of fiber 208. Moreover, the adjusted radial beam characteristics,including position, divergence angle, and/or intensity distribution, ofadjusted beam 226 can be varied based on an extent of decrease in thebend radius and/or the extent of the bend length of VBC fiber 200. Thus,specific beam characteristics may be obtained using this method.

In the current example, first length of fiber 204 having first RIP 212is spliced at splice junction 206 to a second length of fiber 208 havingthe second RIP 214. However, it is possible to use a single fiber havinga single RIP formed to enable perturbation (e.g., by micro-bending) ofthe beam characteristics of optical beam 202 and also to enableconservation of the adjusted beam. Such a RIP may be similar to the RIPsshown in fibers illustrated in FIGS. 17, 18, and/or 19.

FIGS. 7-10 provide experimental results for VBC fiber 200 (shown inFIGS. 2 and 3) and illustrate further a beam response to perturbation ofVBC fiber 200 when a perturbation assembly 210 acts on VBC fiber 200 tobend the fiber. FIGS. 4-6 are simulations and FIGS. 7-10 areexperimental results wherein a beam from a SM 1050 nm source waslaunched into an input fiber (not shown) with a 40 micron (“μm”) corediameter. The input fiber was spliced to first length of fiber 204.

FIG. 4 is an example graph 400 illustrating the calculated profile ofthe lowest-order mode (LP₀₁) for a first length of fiber 204 fordifferent fiber bend radii 402, wherein a perturbation assembly 210involves bending VBC fiber 200. As the fiber bend radius is decreased,an optical beam propagating in VBC fiber 200 is adjusted such that themode shifts radially away from the center 404 of a VBC fiber 200 core(r=0 micron or μm) toward the core/cladding interface (located at r=100microns in this example). Higher-order modes (LP_(ln)) also shift withbending. Thus, a straight or nearly straight fiber (very large bendradius), curve 406 for LP₀₁ is centered at or near the center of VBCfiber 200. At a bend radius of about 6 centimeters (“cm”), curve 408 forLP₀₁ is shifted to a radial position of about 40 μm from the center 404of VBC fiber 200. At a bend radius of about 5 cm, curve 410 for LP₀₁ isshifted to a radial position about 50 μm from the center 404 of VBCfiber 200. At a bend radius of about 4 cm, curve 412 for LP₀₁ is shiftedto a radial position about 60 μm from the center 404 of VBC fiber 200.At a bend radius of about 3 cm, curve 414 for LP₀₁ is shifted to aradial position about 80 μm from the center 404 of VBC fiber 200. At abend radius of about 2.5 cm, a curve 416 for LP₀₁ is shifted to a radialposition about 85 μm from the center 404 of VBC fiber 200. Note that theshape of the mode remains relatively constant (until it approaches theedge of the core), which is a specific property of a parabolic RIP.Although, this property may be desirable in some situations, it is notrequired for the VBC functionality, and other RIPs may be employed.

In an example, if VBC fiber 200 is straightened, LP₀₁ mode will shiftback toward the center of the fiber. Thus, the purpose of second lengthof fiber 208 is to “trap” or confine the adjusted intensity distributionof the beam in a confinement region that is displaced from the center ofthe VBC fiber 200. The splice between first length of fiber 204 andsecond length of fiber 208 is included in the bent region, thus theshifted mode profile will be preferentially launched into one of thering-shaped confinement regions 218 and 220 or be distributed among theconfinement regions. FIGS. 5 and 6 illustrate this effect.

FIG. 5 illustrates an example two-dimensional intensity distribution atsplice junction 206 within second length of fiber 208 when VBC fiber 200is nearly straight. A significant portion of LP₀₁ and LP_(ln) are withinconfinement region 216 of second length of fiber 208. FIG. 6 illustratesthe two-dimensional intensity distribution at splice junction 206 withinsecond length of fiber 208 when VBC fiber 200 is bent with a radiuschosen to preferentially excite confinement region 220 (the outermostconfinement region) of second length of fiber 208. A significant portionof LP₀₁ and LP_(ln) are within confinement region 220 of second lengthof fiber 208.

In an example, second length of fiber 208 confinement region 216 has a100 micron diameter, confinement region 218 is between 120 micron and200 micron in diameter, and confinement region 220 is between 220 micronand 300 micron diameter. Confinement regions 216, 218, and 220 areseparated by 10 um thick rings of fluorosilicate, providing an NA of0.22 for the confinement regions. Other inner and outer diameters forthe confinement regions, thicknesses of the rings separating theconfinement regions, NA values for the confinement regions, and numbersof confinement regions may be employed.

Referring again to FIG. 5, with the noted parameters, when VBC fiber 200is straight about 90% of the power is contained within the centralconfinement region 216, and about 100% of the power is contained withinconfinement regions 216 and 218. Referring now to FIG. 6, when VBC fiber200 is bent to preferentially excite second ring confinement region 220,nearly 75% of the power is contained within confinement region 220, andmore than 95% of the power is contained within confinement regions 218and 220. These calculations include LP₀₁ and two higher-order modes,which is typical in some 2-4 kW fiber lasers.

It is clear from FIGS. 5 and 6 that in the case where a perturbationassembly 210 acts on VBC fiber 200 to bend the fiber, the bend radiusdetermines the spatial overlap of the modal intensity distribution ofthe first length of fiber 204 with the different guiding confinementregions 216, 218, and/or 220 of the second length of fiber 208. Changingthe bend radius can thus change the intensity distribution at the outputof the second length of fiber 208, thereby changing the diameter or spotsize of the beam, and thus also changing its radiance and BPP value.This adjustment of the spot size may be accomplished in an all-fiberstructure, involving no free-space optics and consequently may reduce oreliminate the disadvantages of free-space optics discussed above. Suchadjustments can also be made with other perturbation assemblies thatalter bend radius, bend length, fiber tension, temperature, or otherperturbations discussed below.

In a typical materials processing system (e.g., a cutting or weldingtool), the output of the process fiber is imaged at or near the workpiece by the process head. Varying the intensity distribution as shownin FIGS. 5 and 6 thus enables variation of the beam profile at the workpiece in order to tune and/or optimize the process, as desired. SpecificRIPs for the two fibers were assumed for the purpose of the abovecalculations, but other RIPs are possible, and claimed subject matter isnot limited in this regard.

FIGS. 7-10 depict experimental results (measured intensitydistributions) to illustrate further output beams for various bend radiiof VBC fiber 200 shown in FIG. 2.

In FIG. 7 when VBC fiber 200 is straight, the beam is nearly completelyconfined to confinement region 216. As the bend radius is decreased, theintensity distribution shifts to higher diameters (FIGS. 8-10). FIG. 8depicts the intensity distribution when the bend radius of VBC fiber 200is chosen to shift the intensity distribution preferentially toconfinement region 218. FIG. 9 depicts the experimental results when thebend radius is further reduced and chosen to shift the intensitydistribution outward to confinement region 220 and confinement region218. In FIG. 10, at the smallest bend radius, the beam is nearly a“donut mode,” with most of the intensity in the outermost confinementregion 220.

Despite excitation of the confinement regions from one side at thesplice junction 206, the intensity distributions are nearly symmetricazimuthally because of scrambling within confinement regions as the beampropagates within the VBC fiber 200. Although the beam will typicallyscramble azimuthally as it propagates, various structures orperturbations (e.g., coils) could be included to facilitate thisprocess.

For the fiber parameters used in the experiment shown in FIGS. 7-10,particular confinement regions were not exclusively excited because someintensity was present in multiple confinement regions. This feature mayenable advantageous materials processing applications that are optimizedby having a flatter or distributed beam intensity distribution. Inapplications requiring cleaner excitation of a given confinement region,different fiber RIPs could be employed to enable this feature.

The results shown in FIGS. 7-10 pertain to the particular fibers used inthis experiment, and the details will vary depending on the specifics ofthe implementation. In particular, the spatial profile and divergencedistribution of the output beam and their dependence on bend radius willdepend on the specific RIPs employed, on the splice parameters, and onthe characteristics of the laser source launched into the first fiber.

Different fiber parameters than those shown in FIG. 2 may be used andstill be within the scope of the claimed subject matter. Specifically,different RIPs and core sizes and shapes may be used to facilitatecompatibility with different input beam profiles and to enable differentoutput beam characteristics. Example RIPs for the first length of fiber,in addition to the parabolic-index profile shown in FIG. 2, includeother graded-index profiles, step-index, pedestal designs (i.e., nestedcores with progressively lower refractive indices with increasingdistance from the center of the fiber), and designs with nested coreswith the same refractive index value but with various NA values for thecentral core and the surrounding rings. Example RIPs for the secondlength of fiber, in addition to the profile shown in FIG. 2, includeconfinement fibers with different numbers of confinement regions,non-uniform confinement-region thicknesses, different and/or non-uniformvalues for the thicknesses of the rings surrounding the confinementregions, different and/or non-uniform NA values for the confinementregions, different refractive-index values for the high-index andlow-index portions of the RIP, non-circular confinement regions (such aselliptical, oval, polygonal, square, rectangular, or combinationsthereof), as well as other designs as discussed in further detail withrespect to FIGS. 26-28. Furthermore, VBC fiber 200 and other examples ofa VBC fiber described herein are not restricted to use of two fibers. Insome examples, implementation may include use of one fiber or more thantwo fibers. In some cases, the fiber(s) may not be axially uniform; forexample, they could include fiber Bragg gratings or long-periodgratings, or the diameter could vary along the length of the fiber. Inaddition, the fibers do not have to be azimuthally symmetric (e.g., thecore(s) could have square or polygonal shapes). Various fiber coatings(buffers) may be employed, including high-index or index-matchedcoatings (which strip light at the glass-polymer interface) andlow-index coatings (which guide light by total internal reflection atthe glass-polymer interface). In some examples, multiple fiber coatingsmay be used on VBC fiber 200.

FIGS. 11-16 illustrate cross-sectional views of examples of firstlengths of fiber for enabling adjustment of beam characteristics in aVBC fiber responsive to perturbation of an optical beam propagating inthe first lengths of fiber. Some examples of beam characteristics thatmay be adjusted in the first length of fiber are: angular distribution,azimuthal intensity distribution, beam diameter, beam divergencedistribution, BPP, beam profile (e.g., Gaussian, flat-top), beam shape,divergence, divergence profile, intensity distribution, luminance, M²factor, NA, optical intensity profile, optical mode (e.g., filtering),power density profile, radial beam position, radiance, spatial profiledistribution, spot shape, spot size, or the like, or any combinationthereof. The first lengths of fiber depicted in FIGS. 11-16 anddescribed below are merely examples and do not provide an exhaustiverecitation of the variety of first lengths of fiber that may be utilizedto enable adjustment of beam characteristics in a VBC fiber assembly.Selection of materials, appropriate RIPs, and other variables for thefirst lengths of fiber illustrated in FIGS. 11-16 at least depend on adesired beam output. A wide variety of fiber variables are contemplatedand are within the scope of the claimed subject matter. Thus, claimedsubject matter is not limited by examples provided herein.

In FIG. 11 first length of fiber 1100 comprises a step-index profile1102. FIG. 12 illustrates a first length of fiber 1200 comprising a“pedestal RIP” (i.e., a core comprising a step-index region surroundedby a larger step-index region) 1202. FIG. 13 illustrates first length offiber 1300 comprising a multiple-pedestal RIP 1302.

FIG. 14A illustrates first length of fiber 1400 comprising agraded-index profile 1418 surrounded by a down-doped region 1404. Whenfirst length of fiber 1400 is perturbed, modes may shift radiallyoutward in first length of fiber 1400 (e.g., during bending of firstlength of fiber 1400). Graded-index profile 1402 may be designed topromote maintenance or even compression of modal shape. This design maypromote adjustment of a beam propagating in first length of fiber 1400to generate a beam having a beam intensity distribution concentrated inan outer perimeter of the fiber (i.e., in a portion of the fiber corethat is displaced from the fiber axis). As described above, when theadjusted beam is coupled into a second length of fiber havingconfinement regions, the intensity distribution of the adjusted beam maybe trapped in the outermost confinement region, providing a donut shapedintensity distribution. A beam spot having a narrow outer confinementregion may be useful to enable certain material processing actions.

FIG. 14B illustrates first length of fiber 1406 comprising agraded-index profile 1414 surrounded by a down-doped region 1408 similarto first length of fiber 1400. However, first length of fiber 1406includes a divergence structure 1410 (a lower-index region) as can beseen in profile 1412. The divergence structure 1410 is an area ofmaterial with a lower refractive index than that of the surroundingcore. As the beam is launched into first length of fiber 1406,refraction from divergence structure 1410 causes the beam divergence toincrease in first length of fiber 1406. The amount of increaseddivergence depends on the amount of spatial overlap of the beam with thedivergence structure 1410 and the magnitude of the index differencebetween the divergence structure 1410 and the core material. Divergencestructure 1410 can have a variety of shapes, depending on the inputdivergence distribution and desired output divergence distribution. Inan example, divergence structure 1410 has a triangular or graded indexshape.

FIG. 15 illustrates a first length of fiber 1500 comprising aparabolic-index central region 1508 surrounded by a constant-indexregion 1502, and the constant-index region 1502 is surrounded by alower-index annular layer 1506 and another constant-index region 1504.The lower-index annular layer 1506 helps guide a beam propagating infirst length of fiber 1500. When the propagating beam is perturbed,modes shift radially outward in first length of fiber 1500 (e.g., duringbending of first length of fiber 1500). As one or more modes shiftradially outward, parabolic-index central region 1508 promotes retentionof modal shape. When the modes reach the constant-index region of theRIP 1510, they will be compressed against the lower-index annular layer1506, which may cause preferential excitation of the outermostconfinement region in the second fiber (in comparison to the first fiberRIP shown in FIG. 14). In one implementation, this fiber design workswith a confinement fiber having a central step-index core and a singleannular core. The parabolic-index central region 1508 of the RIPoverlaps with the central step-index core of the confinement fiber. Theconstant-index region 1502 overlaps with the annular core of theconfinement fiber. The constant-index region 1502 of the first fiber isintended to make it easier to move the beam into overlap with theannular core by bending. This fiber design also works with other designsof the confinement fiber.

FIG. 16 illustrates a first length of fiber 1600, having RIP 1602,comprising guiding regions 1604, 1606, 1608, and 1616 bounded bylower-index layers 1610, 1612, and 1614 where the indexes of thelower-index layers 1610, 1612, and 1614 are stepped or, more generally,do not all have the same value. The stepped-index layers may serve tobound the beam intensity to certain guiding regions 1604, 1606, 1608,and/or 1616 when the perturbation assembly 210 (see FIG. 2) acts on thefirst length of fiber 1600. In this way, adjusted beam light may betrapped in the guiding regions over a range of perturbation actions(such as over a range of bend radii, a range of bend lengths, a range ofmicro-bending pressures, and/or a range of acousto-optical signals),allowing for a certain degree of perturbation tolerance before a beamintensity distribution is shifted to a more distant radial position infirst length of fiber 1600. Thus, variation in beam characteristics maybe controlled in a step-wise fashion. The radial widths of the guidingregions 1604, 1606, 1608, and 1616 may be adjusted to achieve a desiredring width, as may be required by an application. Also, a guiding regioncan have a thicker radial width to facilitate trapping of a largerfraction of the incoming beam profile if desired. Guiding region 1606 isan example of such a design.

FIGS. 17-21 depict examples of fibers configured to enable maintenanceand/or confinement of adjusted beam characteristics in the second lengthof fiber (e.g., second length of fiber 208). These fiber designs arereferred to as “ring-shaped confinement fibers” because they contain acentral core surrounded by annular or ring-shaped cores. These designsare merely examples and not an exhaustive recitation of the variety offiber RIPs that may be used to enable maintenance and/or confinement ofadjusted beam characteristics within a fiber. Thus, claimed subjectmatter is not limited to the examples provided herein. Moreover, any ofthe first lengths of fiber described above with respect to FIGS. 11-16may be combined with any of the second length of fiber described FIGS.17-21.

FIG. 17 illustrates a cross-sectional view of an example second lengthof fiber for maintaining and/or confining adjusted beam characteristicsin a VBC fiber assembly. As the perturbed beam is coupled from a firstlength of fiber to second length of fiber 1700, the second length offiber 1700 may maintain at least a portion of the beam characteristicsadjusted in response to perturbation in the first length of fiber withinone or more of confinement regions 1704, 1706, and/or 1708. Secondlength of fiber 1700 has a RIP 1702. Each of confinement regions 1704,1706, and/or 1708 is bounded by a lower index layer 1710 and/or 1712.This design enables second length of fiber 1700 to maintain the adjustedbeam characteristics. As a result, a beam output by second length offiber 1700 will substantially maintain the received adjusted beam asmodified in the first length of fiber giving the output beam adjustedbeam characteristics, which may be customized to a processing task orother application.

Similarly, FIG. 18 depicts a cross-sectional view of an example secondlength of fiber 1800 for maintaining and/or confining beamcharacteristics adjusted in response to perturbation in the first lengthof fiber in a VBC fiber assembly. Second length of fiber 1800 has a RIP1802. However, confinement regions 1808, 1810, and/or 1812 havedifferent thicknesses than confinement regions 1704, 1706, and 1708.Each of confinement regions 1808, 1810, and/or 1812 is bounded by alower index layer 1804 and/or 1806. Varying the thicknesses of theconfinement regions (and/or barrier regions) enables tailoring oroptimization of a confined adjusted radiance profile by selectingparticular radial positions within which to confine an adjusted beam.

FIG. 19 depicts a cross-sectional view of an example second length offiber 1900 having a RIP 1902 for maintaining and/or confining anadjusted beam in a VBC fiber assembly configured to provide variablebeam characteristics. In this example, the number and thicknesses ofconfinement regions 1904, 1906, 1908, and 1910 are different from secondlengths of fiber 1700 and 1800 and the barrier layers 1912, 1914, and1916 are of varied thicknesses as well. Furthermore, confinement regions1904, 1906, 1908, and 1910 have different indexes of refraction andbarrier layers 1912, 1914, and 1916 have different indexes of refractionas well. This design may further enable a more granular or optimizedtailoring of the confinement and/or maintenance of an adjusted beamradiance to particular radial locations within second length of fiber1900. As the perturbed beam is launched from a first length of fiber tosecond length of fiber 1900 the modified beam characteristics of thebeam (having an adjusted intensity distribution, radial position, and/ordivergence angle, or the like, or a combination thereof) is confinedwithin a specific radius by one or more of confinement regions 1904,1906, 1908, and/or 1910 of second length of fiber 1900.

As noted previously, the divergence angle of a beam may be conserved oradjusted and then conserved in the second length of fiber. There are avariety of methods to change the divergence angle of a beam. Thefollowing are examples of fibers configured to enable adjustment of thedivergence angle of a beam propagating from a first length of fiber to asecond length of fiber in a fiber assembly for varying beamcharacteristics. However, these are merely examples and not anexhaustive recitation of the variety of methods that may be used toenable adjustment of divergence of a beam. Thus, claimed subject matteris not limited to the examples provided herein.

FIG. 20 depicts a cross-sectional view of an example second length offiber 2000 having RIP 2002 for modifying, maintaining, and/or confiningbeam characteristics adjusted in response to perturbation in the firstlength of fiber. In this example, second length of fiber 2000 is similarto the previously described second lengths of fiber and forms a portionof the VBC fiber assembly for delivering variable beam characteristicsas discussed above. There are three confinement regions 2004, 2006, and2008 and three barrier layers 2010, 2012, and 2016. Second length offiber 2000 also has a divergence structure 2014 situated within theconfinement region 2006. The divergence structure 2014 is an area ofmaterial with a lower refractive index than that of the surroundingconfinement region. As the beam is launched into second length of fiber2000, refraction from divergence structure 2014 causes the beamdivergence to increase in second length of fiber 2000. The amount ofincreased divergence depends on the amount of spatial overlap of thebeam with the divergence structure 2014 and the magnitude of the indexdifference between the divergence structure 2014 and the core material.By adjusting the radial position of the beam near the launch point intothe second length of fiber 2000, the divergence distribution may bevaried. The adjusted divergence of the beam is conserved in secondlength of fiber 2000, which is configured to deliver the adjusted beamto the process head, another optical system (e.g., fiber-to-fibercoupler or fiber-to-fiber switch), the work piece, or the like, or anycombination thereof. In an example, divergence structure 2014 may havean index dip of about 10⁻⁵-3×10⁻² with respect to the surroundingmaterial. Other values of the index dip may be employed within the scopeof this disclosure and claimed subject matter is not so limited.

FIG. 21 depicts a cross-sectional view of an example second length offiber 2100 having a RIP 2102 for modifying, maintaining, and/orconfining beam characteristics adjusted in response to perturbation inthe first length of fiber. Second length of fiber 2100 forms a portionof a VBC fiber assembly for delivering a beam having variablecharacteristics. In this example, there are three confinement regions2104, 2106, and 2108 and three barrier layers 2110, 2112, and 2116.Second length of fiber 2100 also has a plurality of divergencestructures 2114 and 2118. The divergence structures 2114 and 2118 areareas of graded lower index material. As the beam is launched from thefirst length fiber into second length of fiber 2100, refraction fromdivergence structures 2114 and 2118 causes the beam divergence toincrease. The amount of increased divergence depends on the amount ofspatial overlap of the beam with the divergence structure and themagnitude of the index difference between the divergence structure 2114and/or 2118 and the surrounding core material of confinement regions2106 and 2104 respectively. By adjusting the radial position of the beamnear the launch point into the second length of fiber 2100, thedivergence distribution may be varied. The design shown in FIG. 21allows the intensity distribution and the divergence distribution to bevaried somewhat independently by selecting both a particular confinementregion and the divergence distribution within that conferment region(because each confinement region may include a divergence structure).The adjusted divergence of the beam is conserved in second length offiber 2100, which is configured to deliver the adjusted beam to theprocess head, another optical system, or the work piece. Forming thedivergence structures 2114 and 2118 with a graded or non-constant indexenables tuning of the divergence profile of the beam propagating insecond length of fiber 2100. An adjusted beam characteristic such as aradiance profile and/or divergence profile may be conserved as it isdelivered to a process head by the second fiber. Alternatively, anadjusted beam characteristic such as a radiance profile and/ordivergence profile may be conserved or further adjusted as it is routedby the second fiber through a fiber-to-fiber coupler (“FFC”) and/orfiber-to-fiber switch (“FFS”) and to a process fiber, which delivers thebeam to the process head or the work piece.

FIGS. 26-28 are cross-sectional views illustrating examples of fibersand fiber RIPs configured to enable maintenance and/or confinement ofadjusted beam characteristics of a beam propagating in an azimuthallyasymmetric second length of fiber wherein the beam characteristics areadjusted responsive to perturbation of a first length of fiber coupledto the second length of fiber and/or perturbation of the beam by aperturbation device 110. These azimuthally asymmetric designs are merelyexamples and are not an exhaustive recitation of the variety of fiberRIPs that may be used to enable maintenance and/or confinement ofadjusted beam characteristics within an azimuthally asymmetric fiber.Thus, claimed subject matter is not limited to the examples providedherein. Moreover, any of a variety of first lengths of fiber (e.g., likethose described above) may be combined with any azimuthally asymmetricsecond length of fiber (e.g., like those described in FIGS. 26-28).

FIG. 26 illustrates RIPs at various azimuthal angles of a cross-sectionthrough an elliptical fiber 2600. At a first azimuthal angle 2602,elliptical fiber 2600 has a first RIP 2604. At a second azimuthal angle2606 that is rotated 45° from first azimuthal angle 2602, ellipticalfiber 2600 has a second RIP 2608. At a third azimuthal angle 2610 thatis rotated another 45° from second azimuthal angle 2606, ellipticalfiber 2600 has a third RIP 2612. First, second, and third RIPs 2604,2608, and 2612 are all different.

FIG. 27 illustrates RIPs at various azimuthal angles of a cross-sectionthrough a multicore fiber 2700. At a first azimuthal angle 2702,multicore fiber 2700 has a first RIP 2704. At a second azimuthal angle2706, multicore fiber 2700 has a second RIP 2708. First and second RIPs2704 and 2708 are different. In an example, perturbation device 110 mayact in multiple planes in order to launch the adjusted beam intodifferent regions of an azimuthally asymmetric second fiber.

FIG. 28 illustrates RIPs at various azimuthal angles of a cross-sectionthrough a fiber 2800 having at least one crescent shaped core. In somecases, the corners of the crescent may be rounded, flattened, orotherwise shaped, which may minimize optical loss. At a first azimuthalangle 2802, fiber 2800 has a first RIP 2804. At a second azimuthal angle2806, fiber 2800 has a second RIP 2808. First and second RIPs 2804 and2808 are different.

FIG. 22A illustrates an example of a laser system 2200 including a VBCfiber assembly 2202 configured to provide variable beam characteristics.VBC fiber assembly 2202 comprises a first length of fiber 104, secondlength of fiber 108, and a perturbation device 110. VBC fiber assembly2202 is disposed between feeding fiber 2212 (i.e., the output fiber fromthe laser source) and VBC delivery fiber 2240. VBC delivery fiber 2240may comprise second length of fiber 108 or an extension of second lengthof fiber 108 that modifies, maintains, and/or confines adjusted beamcharacteristics. Beam 2210 is coupled into VBC fiber assembly 2202 viafeeding fiber 2212. VBC Fiber assembly 2202 is configured to vary thecharacteristics of beam 2210 in accordance with the various examplesdescribed above. The output of VBC fiber assembly 2202 is adjusted beam2214 which is coupled into VBC delivery fiber 2240. VBC delivery fiber2240 delivers adjusted beam 2214 to free-space optics assembly 2208,which then couples adjusted beam 2214 into a process fiber 2204.Adjusted beam 2214 is then delivered to process head 2206 by processfiber 2204. The process head can include guided wave optics (such asfibers and fiber coupler), free-space optics such as lenses, mirrors,optical filters, diffraction gratings), beam scan assemblies such asgalvanometer scanners, polygonal mirror scanners, or other scanningsystems that are used to shape the adjusted beam 2214 and deliver theshaped beam to a workpiece.

In laser system 2200, one or more of the free-space optics of free-spaceoptics assembly 2208 may be disposed in an FFC or other beam coupler2216 to perform a variety of optical manipulations of an adjusted beam2214 (represented in FIG. 22A with different dashing than beam 2210).For example, free-space optics assembly 2208 may preserve the adjustedbeam characteristics of adjusted beam 2214. Process fiber 2204 may havethe same RIP as VBC delivery fiber 2240. Thus, the adjusted beamcharacteristics of adjusted beam 2214 may be preserved all the way toprocess head 2206. Process fiber 2204 may comprise a RIP similar to anyof the second lengths of fiber described above, including confinementregions.

Alternatively, as illustrated in FIG. 22B, free-space optics assembly2208 may change the adjusted beam characteristics of adjusted beam 2214by, for example, increasing or decreasing the divergence and/or the spotsize of adjusted beam 2214 (e.g., by magnifying or demagnifying adjustedbeam 2214) and/or otherwise further modifying adjusted beam 2214.Furthermore, process fiber 2204 may have a different RIP than VBCdelivery fiber 2240. Accordingly, the RIP of process fiber 2204 may beselected to preserve additional adjustment of adjusted beam 2214 made bythe free-space optics of free-space optics assembly 2208 to generate atwice adjusted beam 2224 (represented in FIG. 22B with different dashingthan adjusted beam 2214).

FIG. 23 illustrates an example of a laser system 2300 including VBCfiber assembly 2302 disposed between feeding fiber 2312 and VBC deliveryfiber 2340. During operation, beam 2310 is coupled into VBC fiberassembly 2302 via feeding fiber 2312. VBC Fiber assembly 2302 includes afirst length of fiber 104, second length of fiber 108, and aperturbation device 110 and is configured to vary characteristics ofbeam 2310 in accordance with the various examples described above. VBCFiber assembly 2302 generates adjusted beam 2314 output by VBC deliveryfiber 2340. VBC delivery fiber 2340 comprises a second length of fiber108 of fiber for modifying, maintaining, and/or confining adjusted beamcharacteristics in a VBC fiber assembly 2302 in accordance with thevarious examples described above (see FIGS. 17-21, for example). VBCdelivery fiber 2340 couples adjusted beam 2314 into beam switch (“FFS”)2332, which then couples its various output beams to one or more ofmultiple process fibers 2304, 2320, and 2322. Process fibers 2304, 2320,and 2322 deliver adjusted beams 2314, 2328, and 2330 to respectiveprocess heads 2306, 2324, and 2326.

In an example, beam switch 2332 includes one or more sets of free-spaceoptics 2308, 2316, and 2318 configured to perform a variety of opticalmanipulations of adjusted beam 2314. Free-space optics 2308, 2316, and2318 may preserve or vary adjusted beam characteristics of adjusted beam2314. Thus, adjusted beam 2314 may be maintained by the free-spaceoptics or adjusted further. Process fibers 2304, 2320, and 2322 may havethe same or a different RIP as VBC delivery fiber 2340, depending onwhether it is desirable to preserve or further modify a beam passingfrom the free-space optics assemblies 2308, 2316, and 2318 to respectiveprocess fibers 2304, 2320, and 2322. In other examples, one or more beamportions of beam 2310 are coupled to a workpiece without adjustment, ordifferent beam portions are coupled to respective VBC fiber assembliesso that beam portions associated with a plurality of beamcharacteristics can be provided for simultaneous workpiece processing.Alternatively, beam 2310 can be switched to one or more of a set of VBCfiber assemblies.

Routing adjusted beam 2314 through any of free-space optics assemblies2308, 2316, and 2318 enables delivery of a variety of additionallyadjusted beams to process heads 2306, 2324, and 2326. Therefore, lasersystem 2300 provides additional degrees of freedom for varying thecharacteristics of a beam, as well as switching the beam between processheads (“time sharing”) and/or delivering the beam to multiple processheads simultaneously (“power sharing”).

For example, free-space optics in beam switch 2332 may direct adjustedbeam 2314 to free-space optics 2316 configured to preserve the adjustedcharacteristics of adjusted beam 2314. Process fiber 2304 may have thesame RIP as VBC delivery fiber 2340. Thus, the beam delivered to processhead 2306 will be a preserved adjusted beam 2314.

In another example, beam switch 2332 may direct adjusted beam 2314 tofree-space optics 2318 configured to preserve the adjustedcharacteristics of adjusted beam 2314. Process fiber 2320 may have adifferent RIP than VBC delivery fiber 2340 and may be configured withdivergence altering structures as described with respect to FIGS. 20 and21 to provide additional adjustments to the divergence distribution ofadjusted beam 2314. Thus, the beam delivered to process head 2324 willbe a twice adjusted beam 2328 having a different beam divergence profilethan adjusted beam 2314.

Process fibers 2304, 2320, and/or 2322 may comprise a RIP similar to anyof the second lengths of fiber described above, including confinementregions or a wide variety of other RIPs, and claimed subject matter isnot limited in this regard.

In yet another example, free-space optics beam switch 2332 may directadjusted beam 2314 to free-space optics 2308 configured to change thebeam characteristics of adjusted beam 2314. Process fiber 2322 may havea different RIP than VBC delivery fiber 2340 and may be configured topreserve (or alternatively further modify) the new further adjustedcharacteristics of adjusted beam 2314. Thus, the beam delivered toprocess head 2326 will be a twice adjusted beam 2330 having differentbeam characteristics (due to the adjusted divergence profile and/orintensity profile) than adjusted beam 2314.

In FIGS. 22A, 22B, and 23, the optics in the FFC or FFS may adjust thespatial profile and/or divergence profile by magnifying or demagnifyingthe adjusted beam 2214 before launching into the process fiber. They mayalso adjust the spatial profile and/or divergence profile via otheroptical transformations. They may also adjust the launch position intothe process fiber. These methods may be used alone or in combination.

FIGS. 22A, 22B, and 23 merely provide examples of combinations ofadjustments to beam characteristics using free-space optics and variouscombinations of fiber RIPs to preserve or modify adjusted beams 2214 and2314. The examples provided above are not exhaustive and are meant forillustrative purposes only. Thus, claimed subject matter is not limitedin this regard.

FIG. 24 illustrates various examples of perturbation devices,assemblies, or methods (for simplicity referred to collectively hereinas “perturbation device 110”) for perturbing a VBC fiber 200 and/or anoptical beam propagating in VBC fiber 200 according to various examplesprovided herein. Perturbation device 110 may be any of a variety ofdevices, methods, and/or assemblies configured to enable adjustment ofbeam characteristics of a beam propagating in VBC fiber 200. In anexample, perturbation device 110 may be a mandrel 2402, a micro-bend2404 in the VBC fiber 200, flexible tubing 2406, an acousto-optictransducer 2408, a thermal device 2410, a piezoelectric device 2412(e.g., transducer), a grating 2414, a clamp 2416 (or other fastener), amandrel-roller combination 2432, or the like, or any combinationthereof. These are merely examples of perturbation devices 110 and notan exhaustive listing of perturbation devices 110, and claimed subjectmatter is not limited in this regard.

Mandrel 2402 may be used to perturb VBC fiber 200 by providing a formabout which VBC fiber 200 may be bent. As discussed above, reducing thebend radius of VBC fiber 200 moves the intensity distribution of thebeam radially outward. In some examples, mandrel 2402 may be stepped orconically shaped to provide discrete bend radii levels. Alternatively,mandrel 2402 may comprise a cone shape without steps to providecontinuous bend radii for more granular control of the bend radius. Theradius of curvature of mandrel 2402 may be constant (e.g., a cylindricalform) or non-constant (e.g., an oval-shaped form). Similarly, flexibletubing 2406, clamps 2416 (or other varieties of fasteners), or rollers250 may be used to guide and control the bending of VBC fiber 200 aboutmandrel 2402. Furthermore, changing the length over which the fiber isbent at a particular bend radius also may modify the intensitydistribution of the beam. VBC fiber 200 and mandrel 2402 may beconfigured to change the intensity distribution within the first fiberpredictably (e.g., in proportion to the length over which the fiber isbent and/or the bend radius). Rollers 250 may move up and down along atrack 2442 on platform 2434 to change the bend radius of VBC fiber 200.

Clamps 2416 (or other fasteners) may be used to guide and control thebending of VBC fiber 200 with or without a mandrel 2402. Clamps 2416 maymove up and down along a track 2442 or platform 2446. Clamps 2416 mayalso swivel to change bend radius, tension, or direction of VBC fiber200. Controller 2448 may control the movement of clamps 2416.

In another example, perturbation device 110 may be flexible tubing 2406and may guide bending of VBC fiber 200 with or without a mandrel 2402.Flexible tubing 2406 may encase VBC fiber 200. Flexible tubing 2406 maybe made of a variety of materials and may be manipulated usingpiezoelectric transducers controlled by controller 2444. In anotherexample, clamps or other fasteners may be used to move flexible tubing2406.

Micro-bend 2404 in VBC fiber 200 is a local perturbation caused bylateral mechanical stress on the fiber. Micro-bending can cause modecoupling and/or transitions from one confinement region to anotherconfinement region within a fiber, resulting in varied beamcharacteristics of the beam propagating in a VBC fiber 200. Mechanicalstress may be applied by an actuator 2436 that is controlled bycontroller 2440. However, this is merely an example of a method forinducing mechanical stress in VBC fiber 200 and claimed subject matteris not limited in this regard.

Acousto-optic transducer (“AOT”) 2408 may be used to induce perturbationof a beam propagating in the VBC fiber 200 using an acoustic wave. Theperturbation is caused by the modification of the refractive index ofthe fiber by the oscillating mechanical pressure of an acoustic wave.The period and strength of the acoustic wave are related to the acousticwave frequency and amplitude, allowing dynamic control of the acousticperturbation. Thus, a perturbation device 110 including AOT 2408 may beconfigured to vary the beam characteristics of a beam propagating in thefiber. In an example, piezoelectric transducer 2418 may create theacoustic wave and may be controlled by controller or driver 2420. Theacoustic wave induced in AOT 2408 may be modulated to change and/orcontrol the beam characteristics of the optical beam in VBC fiber 200 inreal-time. However, this is merely an example of a method for creatingand controlling an AOT 2408 and claimed subject matter is not limited inthis regard.

Thermal device 2410 may be used to induce perturbation of a beampropagating in VBC fiber 200 using heat. The perturbation is caused bythe modification of the RIP of the fiber induced by heat. Perturbationmay be dynamically controlled by controlling an amount of heattransferred to the fiber and the length over which the heat is applied.Thus, a perturbation device 110 including thermal device 2410 may beconfigured to vary a range of beam characteristics. Thermal device 2410may be controlled by controller 2450.

Piezoelectric device 2412 may be used to induce perturbation of a beampropagating in a VBC fiber using piezoelectric action. The perturbationis caused by the modification of the RIP of the fiber induced by apiezoelectric material attached to the fiber. The piezoelectric materialin the form of a jacket around the bare fiber may apply tension orcompression to the fiber, modifying its refractive index via theresulting changes in density. Perturbation may be dynamically controlledby controlling a voltage to the piezoelectric device 2412. Thus, aperturbation device 110 including piezoelectric device 2412 may beconfigured to vary the beam characteristics over a particular range.

In an example, piezoelectric device 2412 may be configured to displaceVBC fiber 200 in a variety of directions (e.g., axially, radially,and/or laterally) depending on a variety of factors, including how thepiezoelectric device 2412 is attached to VBC fiber 200, the direction ofthe polarization of the piezoelectric materials, the applied voltage,etc. Additionally, bending of VBC fiber 200 is possible using thepiezoelectric device 2412. For example, driving a length ofpiezoelectric material having multiple segments comprising opposingelectrodes can cause a piezoelectric device 2412 to bend in a lateraldirection. Voltage applied to piezoelectric device 2412 by electrode2424 may be controlled by controller 2422 to control displacement of VBCfiber 200. Displacement may be modulated to change and/or control thebeam characteristics of the optical beam in VBC fiber 200 in real-time.However, this is merely an example of a method of controllingdisplacement of a VBC fiber 200 using a piezoelectric device 2412 andclaimed subject matter is not limited in this regard.

Gratings 2414 may be used to induce perturbation of a beam propagatingin a VBC fiber 200. A grating 2414 can be written into a fiber byinscribing a periodic variation of the refractive index into the core.Gratings 2414 such as fiber Bragg gratings can operate as opticalfilters or as reflectors. A long-period grating can induce transitionsamong co-propagating fiber modes. The radiance, intensity profile,and/or divergence profile of a beam comprised of one or more modes canthus be adjusted using a long-period grating to couple one or more ofthe original modes to one or more different modes having differentradiance and/or divergence profiles. Adjustment is achieved by varyingthe periodicity or amplitude of the refractive index grating. Methodssuch as varying the temperature, bend radius, and/or length (e.g.,stretching) of the fiber Bragg grating can be used for such adjustment.VBC fiber 200 having gratings 2414 may be coupled to stage 2426. Stage2426 may be configured to execute any of a variety of functions and maybe controlled by controller 2428. For example, stage 2426 may be coupledto VBC fiber 200 with fasteners 2430 and may be configured to stretchand/or bend VBC fiber 200 using fasteners 2430 for leverage. Stage 2426may have an embedded thermal device and may change the temperature ofVBC fiber 200.

FIG. 25 illustrates an example process 2500 for adjusting and/ormaintaining beam characteristics within a fiber without the use offree-space optics to adjust the beam characteristics. In block 2502, afirst length of fiber and/or an optical beam are perturbed to adjust oneor more optical beam characteristics. Process 2500 moves to block 2504,where the optical beam is launched into a second length of fiber.Process 2500 moves to block 2506, where the optical beam having theadjusted beam characteristics is propagated in the second length offiber. Process 2500 moves to block 2508, where at least a portion of theone or more beam characteristics of the optical beam are maintainedwithin one or more confinement regions of the second length of fiber.The first and second lengths of fiber may be comprised of the samefiber, or they may be different fibers.

Apparatuses for Materials Processing Using Optical Beams

An apparatus for materials processing using optical beams can comprise,for example, VBC fiber 100, including first length of fiber 104 andsecond length of fiber 108, and perturbation device 110 in order tocontrol one or more beam characteristics of optical beam 102, perFIG. 1. Such an apparatus for materials processing using optical beamscan comprise, for example, VBC fiber 200, including first length offiber 204 and second length of fiber 208, and perturbation device 210 inorder to control one or more beam characteristics of optical beam 202,per FIG. 2.

Such an apparatus for materials processing using optical beams cancomprise, for example, first length of fiber 1100, per FIG. 11; firstlength of fiber 2100, per FIG. 12; first length of fiber 1300, per FIG.13; first length of fiber 1400, per FIG. 14A; first length of fiber1406, per FIG. 14B; first length of fiber 1500, per FIG. 15; or firstlength of fiber 1600, per FIG. 16.

Such an apparatus for materials processing using optical beams cancomprise, for example, second length of fiber 1700, per FIG. 17; secondlength of fiber 1800, per FIG. 18; second length of fiber 1900, per FIG.19; second length of fiber 2000, per FIG. 20; or second length of fiber2100, per FIG. 21.

In some examples, a first length of fiber, a second length of fiber, anda perturbation device can be combined in a fiber assembly, such as VBCfiber assembly 2202, per FIG. 22A or FIG. 22B; or VBC fiber assembly2302, per FIG. 23.

A perturbation device (e.g., perturbation device 110) can be configuredto modify one or more beam characteristics of optical beam (e.g.,optical beam 102), during processing, in the first length of fiber(e.g., first length of fiber 104), in the second length of fiber (e.g.,second length of fiber 108), or in the first and second lengths offiber.

In some examples, the perturbation device (e.g., perturbation device110) can modify one or more beam characteristics of an optical beam(e.g., optical beam 102). The modified one or more beam characteristicscan include, for example, one or more of angular distribution, azimuthalintensity distribution, beam diameter, beam profile (e.g., Gaussian,flat-top), beam shape, divergence, divergence profile, divergencedistribution, BPP, intensity distribution, luminance, M² factor, NA,optical intensity, optical mode (e.g., filtering), power density, radialbeam position, radiance, spatial profile distribution, spot shape, orspot size, or any combination thereof.

In some examples, the perturbing effectuated by the perturbation device(e.g., perturbation device 110) can include one or more of bending,bending over a particular length, micro-bending, applying acousto-opticexcitation, thermal perturbation, stretching, applying piezoelectricperturbation, applying clamps (or other fasteners), using a grating, orany combination thereof. FIG. 24 illustrates various examples of suchperturbation devices.

Such an apparatus for materials processing using optical beams canfurther comprise, for example, one or more optical beam sourcesconfigured to generate optical beams, such as laser beams associatedwith fiber-coupled lasers (e.g., diode lasers, fiber lasers), per FIGS.22A, 22B, and/or 23.

Such an apparatus for materials processing using optical beams canfurther comprise, for example, one or more beam couplers, beam switches,free-space optics assemblies, process heads, or any combination thereof.In some examples, characteristics of an adjusted beam (e.g., adjustedbeam 2214) from a VBC fiber assembly (e.g., VBC fiber assembly 2202) canbe preserved in a delivery fiber (e.g., VBC delivery fiber 2240),free-space optics assembly (e.g., free-space optics assembly 2208),process fiber (e.g., process fiber 2204), and/or process head (processhead 2206), per FIG. 22A. In some examples, characteristics of anadjusted beam (e.g., adjusted beam 2214) from a VBC fiber assembly(e.g., VBC fiber assembly 2202) can be preserved in a delivery fiber(e.g., VBC delivery fiber 2240), but then further modified in afree-space optics assembly (e.g., free-space optics assembly 2208), andthen the twice-adjusted beam can be preserved in a process fiber (e.g.,process fiber 2204) and/or process head (process head 2206), per FIG.22B. In some examples, characteristics of an adjusted beam (e.g.,adjusted beam 2314) from a VBC fiber assembly (e.g., VBC fiber assembly2302) can be preserved in a delivery fiber (e.g., VBC delivery fiber2340), but then switched using a beam switch (e.g., beam switch 2332)and preserved or further modified in one or more free-space opticsassemblies (e.g., free-space optics assemblies 2308, 2316, 2318), andthen the once-or-twice-adjusted beams can be preserved in one or moreprocess fibers (e.g., process fiber 2304, 2320, 2322) and/or one or moreprocess heads (e.g., process head 2306, 2324, 2326), per FIG. 23. Suchan apparatus provides for options such as power sharing and time sharingas discussed previously.

Methods of Materials Processing Using Optical Beams

FIG. 29 depicts a first example method of materials processing usingoptical beams. A method of materials processing using an optical beamcomprises launching the optical beam into a first length of fiber havinga first RIP; coupling the optical beam from the first length of fiberinto a second length of fiber having a second RIP and one or moreconfinement regions; modifying one or more beam characteristics of theoptical beam in the first length of fiber, in the second length offiber, or in the first and second lengths of fiber; and/or generating anoutput beam, having the modified one or more beam characteristics of theoptical beam, from the second length of fiber. The first RIP can differfrom the second RIP. The modifying of the one or more beamcharacteristics can comprise changing the one or more beamcharacteristics from a first state (e.g., BPP=0.637 mm-mrad) to a secondstate (e.g., BPP=1.27 mm-mrad). The first state can differ from thesecond state.

In block 2902 of FIG. 29, an optical beam is launched into a firstlength of fiber having a first RIP. In materials processing usingoptical beams, the optical beam can be used, for example, to depositheat in one or more materials for brazing, cladding, glazing,heat-treating, or welding, or any combination thereof.

The optical beam can be generated, for example, by a fiber laser. Such afiber laser can comprise, for example, the first length of fiber havingthe first RIP, a second length of fiber having a second RIP and one ormore confinement regions, and a perturbation device configured to modifyone or more beam characteristics of the optical beam, as previouslydiscussed.

In block 2904 of FIG. 29, the optical beam is coupled from the firstlength of fiber having the first RIP into the second length of fiberhaving the second RIP and the one or more confinement regions. In someexamples, when the second length of fiber has one confinement region,the first RIP can differ from the second RIP; but when the second lengthof fiber has two or more confinement regions, the first RIP can be thesame as or differ from the second RIP.

In block 2906 of FIG. 29, one or more beam characteristics of theoptical beam are modified in the first length of fiber, in the secondlength of fiber, or in the first and second lengths of fiber. Withrespect to blocks 2904 and 2906 of FIG. 29, the modifying can beperformed before the coupling (e.g., modifying in the first length offiber), the coupling can be performed before the modifying (e.g.,modifying in the second length of fiber), or the coupling and modifyingcan be performed concurrently (e.g., modifying in the first and secondlengths of fiber).

The modifying of the one or more beam characteristics can furthercomprise adjusting the one or more beam characteristics, duringprocessing of one or more materials, based on in-process feedback fromone or more sensors, and/or between steps of processing the one or morematerials, based on feedback from the one or more sensors. In someexamples, the modifying of the one or more beam characteristics cancomprise changing the one or more beam characteristics from a firststate to a second state, where the first state differs from the secondstate. The modifying of the one or more beam characteristics can furthercomprise adjusting the perturbation device, in one or more discretesteps and/or in a continuous manner, in order to change the one or morebeam characteristics from the first state to the second state.

The modified one or more beam characteristics can include, for example,one or more of angular distribution, azimuthal intensity distribution,beam diameter, beam divergence distribution, BPP, beam profile (e.g.,Gaussian, flat-top), beam shape, divergence, divergence profile,intensity distribution, luminance, M² factor, NA, optical intensityprofile, optical mode (e.g., filtering), power density profile, radialbeam position, radiance, spatial profile distribution, spot shape, spotsize, or the like, or any combination thereof.

In block 2908 of FIG. 29, an output beam, having the modified one ormore beam characteristics of the optical beam, is generated from thesecond length of fiber. In some examples, a beam shape of the outputbeam can be asymmetric. In some examples, a beam shape of the outputbeam can be symmetric. In some examples, a beam shape of the output beamcomprises two or more discrete spot shapes.

Symmetry of the beam shape can manifest itself, for example, in a spotshape which is symmetric. The spot shape can be, for example, round,square, rectangular, hexagonal, elliptical, have mirror-image symmetry,and/or have rotational symmetry (e.g., 45°, 60°, 90°, 120°, or 180°rotational symmetry).

In some examples, a travel direction of the output beam along one ormore materials, during the materials processing, can be changed from afirst direction to a second direction. The first direction can differfrom the second direction (e.g., a change in the direction of thematerials processing). The second direction can be opposite to the firstdirection (e.g., a reversal of the direction of the materialsprocessing).

FIG. 30 depicts a second example method of materials processing usingoptical beams. A method of materials processing using an optical beamcomprises launching the optical beam into a first length of fiber havinga first RIP; coupling the optical beam from the first length of fiberinto a second length of fiber having a second RIP and two or moreconfinement regions; modifying one or more beam characteristics of theoptical beam in the first length of fiber, in the second length offiber, or in the first and second lengths of fiber; and/or generating anoutput beam, having the modified one or more beam characteristics of theoptical beam, from the second length of fiber. The first RIP can be thesame as the second RIP. The modifying of the one or more beamcharacteristics can comprise changing the one or more beamcharacteristics from a first state (e.g., round spot shape, diameter=5millimeters (“mm”)) to a second state (e.g., rectangular spot shape,length×width=3 mm×6 mm). The first state can differ from the secondstate.

In block 3002 of FIG. 30, an optical beam is launched into a firstlength of fiber having a first RIP. In materials processing usingoptical beams, the optical beam can be used, for example, to depositheat in one or more materials for brazing, cladding, glazing,heat-treating, or welding, or any combination thereof.

The optical beam can be generated, for example, by a fiber laser. Such afiber laser can comprise, for example, the first length of fiber havingthe first RIP, a second length of fiber having a second RIP and two ormore confinement regions, and a perturbation device configured to modifyone or more beam characteristics of the optical beam, as previouslydiscussed.

In block 3004 of FIG. 30, the optical beam is coupled from the firstlength of fiber having the first RIP into the second length of fiberhaving the second RIP and the two or more confinement regions. In someexamples, when the second length of fiber has two or more confinementregions, the first RIP can be the same as or differ from the second RIP.

In block 3006 of FIG. 30, one or more beam characteristics of theoptical beam are modified in the first length of fiber, in the secondlength of fiber, or in the first and second lengths of fiber. Withrespect to blocks 3004 and 3006 of FIG. 30, the modifying can beperformed before the coupling (e.g., modifying in the first length offiber), the coupling can be performed before the modifying (e.g.,modifying in the second length of fiber), or the coupling and modifyingcan be performed concurrently (e.g., modifying in the first and secondlengths of fiber).

The modifying of the one or more beam characteristics can furthercomprise adjusting the one or more beam characteristics, duringprocessing of one or more materials, based on in-process feedback fromone or more sensors, and/or between steps of processing the one or morematerials, based on feedback from the one or more sensors. In someexamples, the modifying of the one or more beam characteristics cancomprise changing the one or more beam characteristics from a firststate to a second state, where the first state differs from the secondstate. The modifying of the one or more beam characteristics can furthercomprise adjusting the perturbation device, in one or more discretesteps and/or in a continuous manner, in order to change the one or morebeam characteristics from the first state to the second state.

The modified one or more beam characteristics can include, for example,one or more of angular distribution, azimuthal intensity distribution,beam diameter, beam divergence distribution, BPP, beam profile (e.g.,Gaussian, flat-top), beam shape, divergence, divergence profile,intensity distribution, luminance, M² factor, NA, optical intensityprofile, optical mode (e.g., filtering), power density profile, radialbeam position, radiance, spatial profile distribution, spot shape, spotsize, or the like, or any combination thereof.

In block 3008 of FIG. 30, an output beam, having the modified one ormore beam characteristics of the optical beam, is generated from thesecond length of fiber. In some examples, a beam shape of the outputbeam can be asymmetric. In some examples, a beam shape of the outputbeam can be symmetric. In some examples, a beam shape of the output beamcan comprise two or more discrete spot shapes.

Symmetry of the beam shape can manifest itself, for example, in a spotshape which is symmetric. The spot shape can be, for example, round,square, rectangular, hexagonal, elliptical, have mirror-image symmetry,and/or have rotational symmetry (e.g., 45°, 60°, 90°, 120°, or 180°rotational symmetry).

In some examples, a travel direction of the output beam along one ormore materials, during the materials processing, can be changed from afirst direction to a second direction. The first direction can differfrom the second direction (e.g., a change in the direction of thematerials processing). The second direction can be opposite to the firstdirection (e.g., a reversal of the direction of the materialsprocessing).

Apparatuses for Materials Processing Using Optical Beams

FIG. 31 depicts a first example apparatus for materials processing usingoptical beams. The materials processing depicted in FIG. 31 can be, forexample, brazing or welding. In some examples, materials involved in thebrazing or welding process can include similar or dissimilar metalalloys, polymers (e.g., thermoplastics), or composite materials.

The first example apparatus can comprise a laser system configured tomodify one or more beam characteristics of an optical beam and togenerate an output beam, having the modified one or more beamcharacteristics of the optical beam, via one or more process heads; aguide configured to supply feedstock, filler, or the like in the form ofpowder, strip, wire, or the like; and/or one or more sensors configuredto provide feedback during processing of one or more materials and/orbetween steps of processing the one or more materials.

The laser system can comprise, for example, laser system 2200 of FIG.22A, including VBC fiber assembly 2202 configured to modify one or morebeam characteristics of optical beam 2210 and to generate output beam2214, having the modified one or more beam characteristics of opticalbeam 2210, via process head 2206; laser system 2200 of FIG. 22B,including VBC fiber assembly 2202 configured to modify one or more beamcharacteristics of optical beam 2210 and to generate output beam 2224,having the modified one or more beam characteristics of optical beam2210, via process head 2206; or laser system 2300 of FIG. 23, includingVBC fiber assembly 2302 configured to modify one or more beamcharacteristics of optical beam 2310 and to generate output beam 2314,2328, and/or 2330, having the modified one or more beam characteristicsof optical beam 2310, via one or more process heads 2306, 2324, and/or2326.

In some examples, materials processing for brazing can use an outputbeam with a round, square, or complex spot shape with dimensions on theorder of 1 mm to 3 mm, and can require a higher divergence than forwelding.

The guide configured to supply feedstock, filler, or the like cancomprise, for example, a nozzle or tube configured to guide powder,strip, wire, or the like to a vicinity of the one or more materialsbeing processed and/or to an intended location of a melt pool. The guidecan be combined with an associated process head.

The guide can be on-axis or off-axis relative to a direction of travelof the output beam with respect to the one or more materials beingprocessed. The guide can have multiple nozzles or tubes. The multiplenozzles or tubes can be symmetrically arranged (e.g., two nozzles ortubes on opposite sides relative to an intended location of the meltpool). Such multiple nozzles or tubes can operate alternately and/orsimultaneously, depending on a mode of operation of the first exampleapparatus.

The one or more sensors configured to provide feedback during processingof one or more materials and/or between steps of processing the one ormore materials can comprise, for example, one or more sensors to monitorgeometry (e.g., height, width), metallurgical properties (e.g.,solidification rate), pressure(s), temperature(s), or the like.

In FIG. 31, first apparatus 3100 comprises process head 3102, guide3104, and/or sensor 3106. First apparatus 3100 can generate output beam3108 via process head 3102. In some examples, a beam shape of outputbeam 3108 can be asymmetric. In some examples, a beam shape of outputbeam 3108 can be symmetric. In some examples, a beam shape of outputbeam 3108 can comprise two or more discrete spot shapes.

Guide 3104 is configured to supply strip or wire 3110 to a vicinity offirst material 3112 and second material 3114 being processed and/or toan intended location of melt pool 3116. As first material 3112 andsecond material 3114 are being processed, process head 3102, guide 3104,output beam 3108, strip or wire 3110, and melt pool 3116 generally movein a direction indicated by arrow 3118.

Guide 3104 and strip or wire 3110 can be on-axis or off-axis relative tothe direction indicated by arrow 3118. In some examples, on-axis guide3104 and strip or wire 3110 can precede output beam 3108 as they bothgenerally move in the direction indicated by arrow 3118. In someexamples, off-axis guide 3104 and strip or wire 3110 can generally movein the direction indicated by arrow 3118, but strip or wire 3110 is thensupplied to melt pool 3116 from a direction other than from the positionof arrow 3118 toward melt pool 3116. In some examples, it can beadvantageous for guide 3104 to supply strip or wire 3110 at a leadingedge of output beam 3108 and/or melt pool 3116 as they move in thedirection indicated by arrow 3118.

Sensor 3106 can monitor the processing of first material 3112 and secondmaterial 3114, provide feedback during processing of first material 3112and/or second material 3114, and/or provide feedback between steps ofprocessing first material 3112 and second material 3114. In someexamples, sensor 3106 can monitor one or more indicators of firstmaterial 3112, second material 3114, and/or melt pool 3116, as indicatedby signature 3120.

In some examples, sensor 3106 can comprise one or more local or globalsensors. In some examples, sensor 3106 can comprise one or more fixedsensors (i.e., an Eulerian reference frame) and/or one or more sensorsmoving with output beam 3108 (i.e., a Lagrangian reference frame).Sensor 3106 can comprise, for example, one or more photodiodes,photomultiplier tubes, pyrometers (using 1- or 2-wavelengths),high-resolution thermal imaging cameras (CCD or CMOS detectors), orspectrometers (visible light, UV light). Sensor 3106 can monitor, forexample, peak and/or average temperature of melt pool 3116,solidification contours and/or dimensions (area, length, and/or width)of melt pool 3116, and/or heating/cooling rates of first material 3112,second material 3114, and/or melt pool 3116. Sensor 3106 can comprise,for example, a global sensor comprising a plurality of fixed CCD or CMOSdetectors configured to monitor the thermal history of first material3112 and/or second material 3114 by sensing signature 3120 (in a form,for example, of radiative emissions) from first material 3112 and/orsecond material 3114 along their length(s) during materials processing.

FIG. 32 depicts a second example apparatus for materials processingusing optical beams. The materials processing depicted in FIG. 32 canbe, for example, cladding. The cladding process can be, for example,omnidirectional cladding or broad area cladding. In some examples,materials involved in the cladding process can include ceramics, similaror dissimilar metal alloys, polymers, or composites.

The second example apparatus can comprise a laser system configured tomodify one or more beam characteristics of an optical beam and togenerate an output beam, having the modified one or more beamcharacteristics of the optical beam, via one or more process heads; aguide configured to supply feedstock, filler, or the like in the form ofpowder, strip, wire, or the like; and/or one or more sensors configuredto provide feedback during processing of one or more materials and/orbetween steps of processing the one or more materials.

The laser system can comprise, for example, laser system 2200 of FIG.22A, including VBC fiber assembly 2202 configured to modify one or morebeam characteristics of optical beam 2210 and to generate output beam2214, having the modified one or more beam characteristics of opticalbeam 2210, via process head 2206; laser system 2200 of FIG. 22B,including VBC fiber assembly 2202 configured to modify one or more beamcharacteristics of optical beam 2210 and to generate output beam 2224,having the modified one or more beam characteristics of optical beam2210, via process head 2206; or laser system 2300 of FIG. 23, includingVBC fiber assembly 2302 configured to modify one or more beamcharacteristics of optical beam 2310 and to generate output beam 2314,2328, and/or 2330, having the modified one or more beam characteristicsof optical beam 2310, via one or more process heads 2306, 2324, and/or2326.

In some examples, the modifying of the one or more beam characteristicscan comprise adjusting the one or more beam characteristics (e.g.,intensity distribution, spatial profile), during processing of one ormore materials, based on in-process feedback from one or more sensors.In some examples, the modifying of the one or more beam characteristicscan comprise adjusting the one or more beam characteristics (e.g., beamdiameter and/or spot size), between steps of processing the one or morematerials, based on feedback from the one or more sensors. In someexamples, the modifying of the one or more beam characteristics cancomprise adjusting the one or more beam characteristics (e.g., beamdivergence), during processing of the one or more materials and betweensteps of processing the one or more materials, based on feedback fromthe one or more sensors.

In some examples, the modifying of the one or more beam characteristicscan comprise changing beam diameter, spot size, and/or beam divergencedistribution to account for switching between omnidirectional claddingand broad area cladding. In some examples, the modifying of the one ormore beam characteristics can comprise adjusting spatial profile topromote smooth overlapping of adjacent tracks of cladding. In someexamples, the modifying of the one or more beam characteristics cancomprise adjusting beam diameter, spot size, and/or intensitydistribution to promote maximizing a melt rate of clad alloy whileminimizing dilution of the clad alloy into base metal (e.g., substratealloy) in order to provide a sharp transition from the clad alloy to thebase metal. In some examples, the modifying of the one or more beamcharacteristics can comprise adjusting beam diameter, spot size, and/orintensity distribution to promote optimizing a cooling rate of depositedcladding to minimize propensity for cracking or delamination (e.g., dueto potential mismatch in coefficient of thermal expansion between theclad alloy and the substrate alloy).

In some examples, materials processing for omnidirectional cladding canuse an output beam with a round spot shape, a diameter of the spot shapegreater than or equal to about 3 mm and less than or equal to about 10mm, and a power greater than or equal to about 4 kW and less than orequal to about 12 kW. In some examples, materials processing for broadarea cladding can use an output beam with a rectangular spot shape, awidth and length greater than or equal to about 10 mm by about 20 mm,and a power greater than or equal to about 5 kW and less than or equalto about 20 kW.

The guide configured to supply feedstock, filler, or the like cancomprise, for example, a nozzle or tube configured to guide powder,strip, wire, or the like to a vicinity of the one or more materialsbeing processed and/or to an intended location of a melt pool. The guidecan be combined with an associated process head.

The guide can be on-axis or off-axis relative to a direction of travelof the output beam with respect to the one or more materials beingprocessed. The guide can have multiple nozzles or tubes. The multiplenozzles or tubes can be symmetrically arranged (e.g., two nozzles ortubes on opposite sides relative to an intended location of the meltpool). Such multiple nozzles or tubes can operate alternately and/orsimultaneously, depending on a mode of operation of the second exampleapparatus.

In some examples, materials processing for unidirectional andomnidirectional cladding can use powder (e.g., blown powder) feedstockguided on-axis. In some examples, materials processing forunidirectional cladding can use wire feedstock guided off-axis. In someexamples, materials processing for broad area cladding can use powder(e.g., blown powder), strip, or wire feedstock guided off-axis.

In some examples, the directionality of a linear cladding process can bechanged quickly. For a linear clad process using a guide with one nozzleor tube, for example, a beam shape can be optimized for a first traveldirection. Then, the beam shape can be quickly inverted for a secondtravel direction. The single nozzle or tube can operate in both traveldirections. For a linear clad process using a guide with two nozzles ortubes, for example, a beam shape can be optimized for a first traveldirection and an associated one of the nozzles or tubes operated in thefirst travel direction. Then, the beam shape can be quickly inverted fora second travel direction and the other one of the nozzles or tubesoperated in the second travel direction (i.e., nozzles or tubes operatealternately).

The one or more sensors configured to provide feedback during processingof one or more materials and/or between steps of processing the one ormore materials can comprise, for example, one or more sensors to monitorgeometry (e.g., height, width), metallurgical properties (e.g.,solidification rate), pressure(s), temperature(s), or the like. In someexamples, a thermal imaging tool or pyrometer can measure heating and/orcooling rates. In some examples, a geometry monitor can measure height,width, and/or other physical measurements related to clad deposition,such as overlap with adjacent tracks of cladding, or roughness oroverall shape.

In FIG. 32, second apparatus 3200 comprises process head 3202, guides3204, and/or sensor 3206. Second apparatus 3200 can generate output beam3208 via process head 3202. In some examples, a beam shape of outputbeam 3208 can be asymmetric. In some examples, a beam shape of outputbeam 3208 can be symmetric. In some examples, a beam shape of outputbeam 3208 can comprise two or more discrete spot shapes.

Guides 3204 are configured to supply powder 3222 (e.g., metal powder) toa vicinity of material 3212 being processed and/or to an intendedlocation of melt pool 3216. Guides 3204 can comprise, for example,water-cooled powder nozzles. As material 3212 is being processed,process head 3202, guides 3204, output beam 3208, melt pool 3216, andpowder 3222 generally move in a direction indicated by arrow 3218.Shielding gas 3224 (e.g., inert gas) can be injected between guides 3204to prevent powder 3222 from escaping upward between guides 3204. Shroudgas (e.g., inert gas) (not shown) can be used to prevent powder 3222from escaping laterally once it exits guides 3204 and to preventoxidation of heated material 3212.

Guides 3204 and powder 3222 can be on-axis or off-axis relative to thedirection indicated by arrow 3218. In some examples, on-axis guides 3204and powder 3222 can precede and follow output beam 3208 as they allgenerally move in the direction indicated by arrow 3218. In someexamples, off-axis guides 3204 and powder 3222 can generally move in thedirection indicated by arrow 3218, but powder 3222 is then supplied tomelt pool 3216 from directions other than from the position of arrow3218 toward melt pool 3216 or in the direction of arrow 3218. In someexamples, it can be advantageous for guides 3204 to supply powder 3222at leading and trailing edges of output beam 3208 and/or melt pool 3216as they move in the direction indicated by arrow 3218.

In some examples, processing of material 3212 can result in theformation of clad layer 3226, bonding zone 3228, and/or heat-affectedzone 3230.

Sensor 3206 can monitor the processing of material 3212, providefeedback during the processing of material 3212, and/or provide feedbackbetween steps of processing material 3212. In some examples, sensor 3206can monitor one or more indicators of material 3212 and/or melt pool3216, as indicated by signature 3220.

In some examples, sensor 3206 can comprise one or more local or globalsensors. In some examples, sensor 3206 can comprise one or more fixedsensors (i.e., an Eulerian reference frame) and/or one or more sensorsmoving with output beam 3208 (i.e., a Lagrangian reference frame).Sensor 3206 can comprise, for example, one or more photodiodes,photomultiplier tubes, pyrometers (using 1- or 2-wavelengths),high-resolution thermal imaging cameras (CCD or CMOS detectors), orspectrometers (visible light, UV light). Sensor 3206 can monitor, forexample, peak and/or average temperature of melt pool 3216,solidification contours and/or dimensions (area, length, and/or width)of melt pool 3216, and/or heating/cooling rates of processing material3212 and/or melt pool 3216. Sensor 3206 can comprise, for example, aglobal sensor comprising a plurality of fixed CCD or CMOS detectorsconfigured to monitor the thermal history of processing material 3212 bysensing signature 3220 (in a form, for example, of radiative emissions)from processing material 3212 along its length during materialsprocessing.

FIG. 33 depicts a third example apparatus for materials processing usingoptical beams. The materials processing depicted in FIG. 33 can be, forexample, glazing or heat-treating. Glazing can include surface meltingand subsequent rapid solidification of a thin layer of material (e.g.,on the order of 100 μm). In some examples, materials involved in theglazing process can include ceramics and metals (e.g., ferritic ductileiron; FeNiCrAl, NiCr, and/or NiCrAl alloys; 304 stainless steel; 614 Albronze (Al=aluminum, Cr=chromium, Fe=iron, and Ni=nickel)).Heat-treating can include, for example, annealing, case hardening,normalizing, precipitation strengthening, quenching (includingself-quenching), softening, stress relieving, and/or tempering. In someexamples, materials involved in the heat-treating process can includeglass, metals, or polymers. Other heat-treating applications can includedirect heating of adhesives, polymers, or resins immediately prior totheir use in joining materials, as well as after joining the materialsto apply heat for curing or hardening the joint.

The third example apparatus can comprise a laser system configured tomodify one or more beam characteristics of an optical beam and togenerate an output beam, having the modified one or more beamcharacteristics of the optical beam, via one or more process heads;and/or one or more sensors configured to provide feedback duringprocessing of one or more materials and/or between steps of processingthe one or more materials.

The laser system can comprise, for example, laser system 2200 of FIG.22A, including VBC fiber assembly 2202 configured to modify one or morebeam characteristics of optical beam 2210 and to generate output beam2214, having the modified one or more beam characteristics of opticalbeam 2210, via process head 2206; laser system 2200 of FIG. 22B,including VBC fiber assembly 2202 configured to modify one or more beamcharacteristics of optical beam 2210 and to generate output beam 2224,having the modified one or more beam characteristics of optical beam2210, via process head 2206; or laser system 2300 of FIG. 23, includingVBC fiber assembly 2302 configured to modify one or more beamcharacteristics of optical beam 2310 and to generate output beam 2314,2328, and/or 2330, having the modified one or more beam characteristicsof optical beam 2310, via one or more process heads 2306, 2324, and/or2326.

In some examples, the modifying of the one or more beam characteristicscan comprise adjusting beam diameter, spot size, and/or beam divergencedistribution in real time in order to match a required heat treat trackgeometry for the material being processed. In some examples, themodifying of the one or more beam characteristics can comprise adjustingintensity distribution and/or spatial profile to maximize productivitywhile limiting melting of the material being processed. In someexamples, the modifying of the one or more beam characteristics cancomprise adjusting the one or more beam characteristics in order tooptimize a heating rate profile or a cooling rate profile for thealloys, microstructures, thicknesses, and/or preferred hardness depthsof the material being processed. In some examples, the modifying of theone or more beam characteristics can comprise axially rotating a beamprofile in order to match a 2D/3D directionality of the materialsprocess.

In some examples, materials processing for glazing and/or heat-treatingcan use an output beam with a rectangular spot shape and a power greaterthan or equal to about 4 kW and less than or equal to about 50 kW. Insome examples, a homogeneous (e.g., flat-top) intensity distribution canprovide even depth of melting for glazing, case depth for hardening, ortempered zone for softening. Alternatively, varying one or more of thebeam characteristics to provide different intensity profiles within, forexample, a rectangular spot can tailor the processed depth across therectangular spot shape.

The one or more sensors configured to provide feedback during processingof one or more materials and/or between steps of processing the one ormore materials can comprise, for example, one or more sensors to monitorgeometry (e.g., height, width), metallurgical properties (e.g.,hardness), temperature(s), or the like.

In FIG. 33, third apparatus 3300 comprises process head 3302 and/orsensor 3306. Third apparatus 3300 can generate output beam 3308 viaprocess head 3302. In some examples, a beam shape of output beam 3308can be asymmetric. In some examples, the beam shape of output beam 3308can be symmetric. In some examples, the beam shape of output beam 3308can comprise two or more discrete spot shapes. In FIG. 33, the beamshape of output beam 3308 is depicted as rectangular, with a width ‘x’and length ‘y’.

In some examples, processing of material 3312 can result in theformation of zone 3332 of hardening or softening. As depicted in FIG.33, zone 3332 can have a maximum depth ‘d’.

Sensor 3306 can monitor the processing of material 3312, providefeedback during the processing of material 3312, and/or provide feedbackbetween steps of processing material 3312. In some examples, sensor 3306can monitor one or more indicators of material 3312, as indicated bysignature 3320.

In some examples, sensor 3306 can comprise one or more local or globalsensors. In some examples, sensor 3306 can comprise one or more fixedsensors (i.e., an Eulerian reference frame) and/or one or more sensorsmoving with output beam 3308 (i.e., a Lagrangian reference frame).Sensor 3306 can comprise, for example, one or more photodiodes,photomultiplier tubes, pyrometers (using 1- or 2-wavelengths),high-resolution thermal imaging cameras (CCD or CMOS detectors), orspectrometers (visible light, UV light). Sensor 3306 can monitor, forexample, peak and/or average temperature of processing material 3312,dimensions (area, length, and/or width) of processing material 3312,and/or heating/cooling rates of processing material 3312. Sensor 3306can comprise, for example, a global sensor comprising a plurality offixed CCD or CMOS detectors configured to monitor the thermal history ofprocessing material 3312 by sensing signature 3320 (in a form, forexample, of radiative emissions) from processing material 3312 along itslength during materials processing.

FIGS. 34A and 34B depict example output beams having two discrete spotshapes.

In FIG. 34A, output beam 3400 has first spot shape 3402 and second spotshape 3404. Because it is round, first spot shape 3402 exhibitsmirror-image symmetry at any orientation of a mirror through its centerand rotational symmetry at any angle of rotation. Second spot shape 3404exhibits only mirror-image symmetry through its center in a horizontalorientation, as depicted. The limited symmetry of second spot shape 3404limits the overall symmetry of output beam 3400.

In some examples, output beam 3400 can be optimized for materialsprocessing in a travel direction indicated by arrow 3406.

In FIG. 34B, output beam 3410 has first spot shape 3412 and second spotshape 3414. Because it is round, first spot shape 3412 exhibitsmirror-image symmetry at any orientation of a mirror through its centerand rotational symmetry at any angle of rotation. Second spot shape 3414exhibits only mirror-image symmetry through its center in a horizontalorientation, as depicted. The limited symmetry of second spot shape 3414limits the overall symmetry of output beam 3410.

In some examples, output beam 3410 can be optimized for materialsprocessing in a travel direction indicated by arrow 3416.

As discussed with reference to the unidirectional and omnidirectionalcladding examples, the directionality of a linear cladding process canbe changed quickly. For a linear clad process using a guide with twonozzles or tubes, for example, output beam 3400 of FIG. 34A, havingfirst spot shape 3402 and second spot shape 3404, and an associated oneof the nozzles or tubes can be optimized for the travel directionindicated by arrow 3406 (e.g., to go “right”). First spot shape 3402 canprovide pre-heating of a material before a cladding process and secondspot shape 3404 can provide the main heating of the material during thecladding process. Then, the beam shape can be quickly inverted. Outputbeam 3410 of FIG. 34B, having first spot shape 3412 and second spotshape 3414, and the other one of the nozzles or tubes can be optimizedfor the travel direction indicated by arrow 3416 (e.g., to go “left”).First spot shape 3412 can provide pre-heating of the material before thecladding process and second spot shape 3414 can provide the main heatingof the material during the cladding process.

Alternatively, the directional linear cladding process describedpreviously can operate in the opposite directions from that indicated byarrow 3406 in FIG. 34A and arrow 3416 in FIG. 34B. In this oppositedirection (not shown), second spot shape 3404 and second spot shape 3414can provide post-heating effects for the cladding process (e.g.,tempering, stress relieving, or reducing a cooling rate to reducepropensity for cracking).

FIGS. 35A-35D depict example output beams having two discrete spotshapes.

In FIG. 35A, output beam 3500 has first spot shape 3502 and second spotshape 3504. Because it is round, first spot shape 3502 exhibitsmirror-image symmetry at any orientation of a mirror through its center,and rotational symmetry at any angle of rotation. Because it is round,second spot shape 3504 also exhibits mirror-image symmetry at anyorientation of a mirror through its center and rotational symmetry atany angle of rotation. Output beam 3500, the combination of first spotshape 3502 and second spot shape 3504, exhibits only mirror-imagesymmetry through the respective centers of first spot shape 3502 andsecond spot shape 3504 in a horizontal orientation, as depicted.

In some examples, output beam 3500 can be optimized for materialsprocessing in a travel direction indicated by arrow 3506.

In FIG. 35B, output beam 3510 has first spot shape 3512 and second spotshape 3514. Because it is round, first spot shape 3512 exhibitsmirror-image symmetry at any orientation of a mirror through its center,and rotational symmetry at any angle of rotation. Because it is round,second spot shape 3514 also exhibits mirror-image symmetry at anyorientation of a mirror through its center and rotational symmetry atany angle of rotation. Output beam 3510, the combination of first spotshape 3512 and second spot shape 3514, exhibits only mirror-imagesymmetry through the respective centers of first spot shape 3512 andsecond spot shape 3514 in a vertical orientation, as depicted.

In some examples, output beam 3510 can be optimized for materialsprocessing in a travel direction indicated by arrow 3516.

In FIG. 35C, output beam 3520 has first spot shape 3522 and second spotshape 3524. Because it is round, first spot shape 3522 exhibitsmirror-image symmetry at any orientation of a mirror through its center,and rotational symmetry at any angle of rotation. Because it is round,second spot shape 3524 also exhibits mirror-image symmetry at anyorientation of a mirror through its center and rotational symmetry atany angle of rotation. Output beam 3520, the combination of first spotshape 3522 and second spot shape 3524, exhibits only mirror-imagesymmetry through the respective centers of first spot shape 3522 andsecond spot shape 3524 in a horizontal orientation, as depicted.

In some examples, output beam 3520 can be optimized for materialsprocessing in a travel direction indicated by arrow 3526.

In FIG. 35D, output beam 3530 has first spot shape 3532 and second spotshape 3534. Because it is round, first spot shape 3532 exhibitsmirror-image symmetry at any orientation of a mirror through its center,and rotational symmetry at any angle of rotation. Because it is round,second spot shape 3534 also exhibits mirror-image symmetry at anyorientation of a mirror through its center and rotational symmetry atany angle of rotation. Output beam 3530, the combination of first spotshape 3532 and second spot shape 3534, exhibits only mirror-imagesymmetry through the respective centers of first spot shape 3532 andsecond spot shape 3534 in a vertical orientation, as depicted.

In some examples, output beam 3530 can be optimized for materialsprocessing in a travel direction indicated by arrow 3536.

As discussed previously, the modifying of the one or more beamcharacteristics can comprise axially rotating a beam profile in order tomatch a 2D/3D directionality of the materials process. FIGS. 35A-35Ddepict examples of such axial rotations, starting from FIG. 35A, inwhich FIG. 35B depicts a 90° degree rotation counterclockwise, FIG. 35Cdepicts a 180° rotation clockwise or counterclockwise, and FIG. 35Ddepicts a 90° degree rotation clockwise.

Although FIGS. 35A-35D depict n×90° degree rotations (n=0, ±1, ±2, . . .), the rotations can also be in any degree increment desired (e.g., 72°,60°, 45°, 40°, 36°, 30°, 22.5°, 20°, 15°, 10° to the shared centerlineof the beams).

Having described and illustrated the general and specific principles ofexamples of the presently disclosed technology, it should be apparentthat the examples may be modified in arrangement and detail withoutdeparting from such principles. We claim all modifications and variationcoming within the spirit and scope of the following claims.

We claim:
 1. A method of materials processing using an optical beam andfirst and second lengths of fiber having, respectively, first and secondrefractive-index profiles (RIPs) that are different from each other, themethod comprising: launching the optical beam into the first length offiber having the first refractive-index profile (RIP); modifying one ormore beam characteristics of the optical beam so as to change the one ormore beam characteristics from a first state to a second state that isdifferent from the first state; through a fiber-coupling interface thatfunctionally directly couples the first and second lengths of fiber,coupling the optical beam from the first length of fiber into the secondlength of fiber having the second RIP defined by multiple confinementregions; and generating at an output of the second length of fiber anoutput beam having the modified one or more beam characteristics.
 2. Themethod of claim 1, further comprising: generating the output beam havingthe modified one or more beam characteristics by confining at least ofportion of the optical beam within at least one of the multipleconfinement regions of the second length of fiber.
 3. The method ofclaim 1, further comprising: using the output beam for one or more ofbrazing, cladding, glazing, heat-treating, or welding, or anycombination thereof, of one or more materials.
 4. The method of claim 1,wherein the modifying of the one or more beam characteristics furthercomprises adjusting the one or more beam characteristics, duringprocessing of one or more materials, based on in-process feedback fromone or more sensors.
 5. The method of claim 1, wherein the modifying ofthe one or more beam characteristics further comprises adjusting the oneor more beam characteristics, between steps of processing one or morematerials, based on feedback from one or more sensors.
 6. The method ofclaim 1, wherein the modifying of the one or more beam characteristicsfurther comprises adjusting a perturbation device in one or morediscrete steps in order to change the one or more beam characteristicsfrom the first state to the second state.
 7. The method of claim 1,wherein the modifying of the one or more beam characteristics furthercomprises adjusting a perturbation device in a continuous manner inorder to change the one or more beam characteristics from the firststate to the second state.
 8. The method of claim 1, wherein a beamshape of the output beam is asymmetric.
 9. The method of claim 1,further comprising: changing a travel direction of the output beam alongone or more materials, during the materials processing, from a firstdirection to a second direction; wherein the first direction differsfrom the second direction.
 10. The method of claim 9, wherein the seconddirection is opposite to the first direction.
 11. The method of claim 1,in which the modifying comprises imparting transverse displacement tothe optical beam in response to applied perturbation.
 12. The method ofclaim 1, in which the first length of fiber includes an input forreceiving the optical beam from an input fiber.
 13. The method of claim1, in which the first length of fiber includes an output fused to aninput of the second length of fiber.
 14. The method of claim 1, in whichthe fiber-coupling interface includes an index-matching material. 15.The method of claim 1, in which the fiber-coupling interface includes asplice.
 16. The method of claim 1, in which the fiber-coupling interfaceincludes a fiber joint.
 17. The method of claim 1, in which thefiber-coupling interface includes a connector.
 18. The method of claim1, in which the fiber-coupling interface maintains a substantiallyunaltered operative relationship between the first and second RIPs.